Recent user-visible changes to Tcl:

SCCS: @(#) changes 1.171 96/10/14 12:59:16

1. No more [command1] [command2] construct for grouping multiple
commands on a single command line.

2. Semi-colon now available for grouping commands on a line.

3. For a command to span multiple lines, must now use backslash-return
at the end of each line but the last.

4. "Var" command has been changed to "set".

5. Double-quotes now available as an argument grouping character.

6. "Return" may be used at top-level.

7. More backslash sequences available now.  In particular, backslash-newline
may be used to join lines in command files.

8. New or modified built-in commands:  case, return, for, glob, info,
print, return, set, source, string, uplevel.

9. After an error, the variable "errorInfo" is filled with a stack
trace showing what was being executed when the error occurred.

10. Command abbreviations are accepted when parsing commands, but
are not recommended except for purely-interactive commands.

11. $, set, and expr all complain now if a non-existent variable is
referenced.

12. History facilities exist now.  See Tcl.man and Tcl_RecordAndEval.man.

13. Changed to distinguish between empty variables and those that don't
exist at all.  Interfaces to Tcl_GetVar and Tcl_ParseVar have changed
(NULL return value is now possible).  *** POTENTIAL INCOMPATIBILITY ***

14. Changed meaning of "level" argument to "uplevel" command (1 now means
"go up one level", not "go to level 1"; "#1" means "go to level 1").
*** POTENTIAL INCOMPATIBILITY ***

15. 3/19/90 Added "info exists" option to see if variable exists.

16. 3/19/90 Added "noAbbrev" variable to prohibit command abbreviations.

17. 3/19/90 Added extra errorInfo option to "error" command.

18. 3/21/90 Double-quotes now only affect space:  command, variable,
and backslash substitutions still occur inside double-quotes.
*** POTENTIAL INCOMPATIBILITY ***

19. 3/21/90 Added support for \r.

20. 3/21/90 List, concat, eval, and glob commands all expect at least
one argument now.  *** POTENTIAL INCOMPATIBILITY ***

21. 3/22/90 Added "?:" operators to expressions.

22. 3/25/90 Fixed bug in Tcl_Result that caused memory to get trashed.

------------------- Released version 3.1 ---------------------

23. 3/29/90 Fixed bug that caused "file a.b/c ext" to return ".b/c".

24. 3/29/90 Semi-colon is not treated specially when enclosed in
double-quotes.

------------------- Released version 3.2 ---------------------

25. 4/16/90 Rewrote "exec" not to use select or signals anymore.
Should be more Sys-V compatible, and no slower in the normal case.

26. 4/18/90 Rewrote "glob" to eliminate GNU code (there's no GNU code
left in Tcl, now), and added Tcl_TildeSubst procedure.  Added automatic
tilde-substitution in many commands, including "glob".

------------------- Released version 3.3 ---------------------

27. 7/11/90 Added "Tcl_AppendResult" procedure.

28. 7/20/90 "History" with no options now defaults to "history info"
rather than to "history redo".  Although this is a backward incompatibility,
it should only be used interactively and thus shouldn't present any
compatibility problems with scripts.

29. 7/20/90 Added "Tcl_GetInteger", "Tcl_GetDouble", and "Tcl_GetBoolean"
procedures.

30. 7/22/90 Removed "Tcl_WatchInterp" procedure:  doesn't seem to be
necessary, since the same effect can be achieved with the deletion
callbacks on individual commands.  *** POTENTIAL INCOMPATIBILITY ***

31. 7/23/90 Added variable tracing:  Tcl_TraceVar, Tcl_UnTraceVar,
and Tcl_VarTraceInfo procedures, "trace" command.

32. 8/9/90 Mailed out list of all bug fixes since 3.3 release.

33. 8/29/90 Fixed bugs in Tcl_Merge relating to backslashes and
semi-colons.  Mailed out patch.

34. 9/3/90 Fixed bug in tclBasic.c: quotes weren't quoting ]'s.
Mailed out patch.

35. 9/19/90 Rewrote exec to always use files both for input and
output to the process.  The old pipe-based version didn't work if
the exec'ed process forked a child and then exited:  Tcl waited
around for stdout to get closed, which didn't happen until the
grandchild exited.

36. 11/5/90 ERR_IN_PROGRESS flag wasn't being cleared soon enough
in Tcl_Eval, allowing error messages from different commands to
pile up in $errorInfo.  Fixed by re-arranging code in Tcl_Eval that
re-initializes result and ERR_IN_PROGRESS flag.  Didn't mail out
patch:  changes too complicated to describe.

37. 12/19/90 Added Tcl_VarEval procedure as a convenience for
assembling and executing Tcl commands.

38. 1/29/91 Fixed core leak in Tcl_AddErrorInfo.  Also changed procedure
and Tcl_Eval so that first call to Tcl_AddErrorInfo need not come from
Tcl_Eval.

----------------- Released version 5.0 with Tk ------------------

39. 4/3/91 Removed change bars from manual entries, leaving only those
that came after version 3.3 was released.

40. 5/17/91 Changed tests to conform to Mary Ann May-Pumphrey's approach.

41. 5/23/91 Massive revision to Tcl parser to simplify the implementation
of string and floating-point support in expressions.  Newlines inside
[] are now treated as command separators rather than word separators
(this makes newline treatment consistent throughout Tcl).
*** POTENTIAL INCOMPATIBILITY ***

42. 5/23/91 Massive rewrite of expression code to support floating-point
values and simple string comparisons.  The C interfaces to expression
routines have changed (Tcl_Expr is replaced by Tcl_ExprLong, Tcl_ExprDouble,
etc.), but all old Tcl expression strings should be accepted by the new
expression code.
*** POTENTIAL INCOMPATIBILITY ***

43. 5/23/91 Modified tclHistory.c to check for negative "keep" value.

44. 5/23/91 Modified Tcl_Backslash to handle backslash-newline.  It now
returns 0 to indicate that a backslash sequence should be replaced by
no character at all.
*** POTENTIAL INCOMPATIBILITY ***

45. 5/29/91 Modified to use ANSI C function prototypes.  Must set
"USE_ANSI" switch when compiling to get prototypes.

46. 5/29/91 Completed test suite by providing tests for all of the
built-in Tcl commands.

47. 5/29/91 Changed Tcl_Concat to eliminate leading and trailing
white-space in each of the things it concatenates and to ignore
elements that are empty or have only white space in them.  This
produces cleaner output from the "concat" command.
*** POTENTIAL INCOMPATIBILITY ***

48. 5/31/91 Changed "set" command and Tcl_SetVar procedure to return
new value of variable.

49. 6/1/91 Added "while" and "cd" commands.

50. 6/1/91 Changed "exec" to delete the last character of program
output if it is a newline.  In most cases this makes it easier to
process program-generated output.
*** POTENTIAL INCOMPATIBILITY ***

51. 6/1/91 Made sure that pointers are never used after freeing them.

52. 6/1/91 Fixed bug in TclWordEnd where it wasn't dealing with
[] inside quotes correctly.

53. 6/8/91 Fixed exec.test to accept return values of either 1 or
255 from "false" command.

54. 7/6/91 Massive overhaul of variable management.  Associative
arrays now available, along with "unset" command (and Tcl_UnsetVar
procedure).  Variable traces have been completely reworked:
interfaces different both from Tcl and C, and multiple traces may
exist on same variable.  Can no longer redefine existing local
variable to be global.  Calling sequences have changed slightly
for Tcl_GetVar and Tcl_SetVar ("global" is now "flags"). Tcl_SetVar
can fail and return a NULL result.  New forms of variable-manipulation
procedures:  Tcl_GetVar2, Tcl_SetVar2, etc.  Syntax of variable
$-notation changed to support array indexing.
*** POTENTIAL INCOMPATIBILITY ***

55. 7/6/91 Added new list-manipulation procedures:  Tcl_ScanElement,
Tcl_ConvertElement, Tcl_AppendElement.

56. 7/12/91 Created new procedure Tcl_EvalFile, which does most of the
work of the "source" command.

57. 7/20/91 Major reworking of "exec" command to allow pipelines,
more redirection, background.  Added new procedures Tcl_Fork,
Tcl_WaitPids, Tcl_DetachPids, and Tcl_CreatePipeline.  The old
"< input" notation has been replaced by "<< input" ("<" is for
redirection from a file).  Also handles error returns and abnormal
terminations (e.g. signals) differently.
*** POTENTIAL INCOMPATIBILITY ***

58. 7/21/91 Added "append" and "lappend" commands.

59. 7/22/91 Reworked error messages and manual entries to use
?x? as the notation for an optional argument x, instead of [x].  The
bracket notation was often confused with the use of brackets for
command substitution.  Also modified error messages to be more
consistent.

60. 7/23/91 Tcl_DeleteCommand now returns an indication of whether
or not the command actually existed, and the "rename" command uses
this information to return an error if an attempt is made to delete
a non-existent command.
*** POTENTIAL INCOMPATIBILITY ***

61. 7/25/91 Added new "errorCode" mechanism, along with procedures
Tcl_SetErrorCode, Tcl_UnixError, and Tcl_ResetResult.  Renamed
Tcl_Return to Tcl_SetResult, but left a #define for Tcl_Return to
avoid compatibility problems.

62. 7/26/91 Extended "case" command with alternate syntax where all
patterns and commands are together in a single list argument:  makes
it easier to write multi-line case statements.

63. 7/27/91 Changed "print" command to perform tilde-substitution on
the file name.

64. 7/27/91 Added "tolower", "toupper", "trim", "trimleft", and "trimright"
options to "string" command.

65. 7/29/91 Added "atime", "mtime", "size", and "stat" options to "file"
command.

66. 8/1/91 Added "split" and "join" commands.

67. 8/11/91 Added commands for file I/O, including "open", "close",
"read", "gets", "puts", "flush", "eof", "seek", and "tell".

68. 8/14/91 Switched to use a hash table for command lookups.  Command
abbreviations no longer have direct support in the Tcl interpreter, but
it should be possible to simulate them with the auto-load features
described below.  The "noAbbrev" variable is no longer used by Tcl.
*** POTENTIAL INCOMPATIBILITY ***

68.5 8/15/91 Added support for "unknown" command, which can be used to
complete abbreviations, auto-load library files, auto-exec shell
commands, etc.

69. 8/15/91 Added -nocomplain switch to "glob" command.

70. 8/20/91 Added "info library" option and TCL_LIBRARY #define.  Also
added "info script" option.

71. 8/20/91 Changed "file" command to take "option" argument as first
argument (before file name), for consistency with other Tcl commands.
*** POTENTIAL INCOMPATIBILITY ***

72. 8/20/91 Changed format of information in $errorInfo variable:
comments such as 
    ("while" body line 1)
are now on separate lines from commands being executed.
*** POTENTIAL INCOMPATIBILITY ***

73. 8/20/91 Changed Tcl_AppendResult so that it (eventually) frees
large buffers that it allocates.

74. 8/21/91 Added "linsert", "lreplace", "lsearch", and "lsort"
commands.

75. 8/28/91 Added "incr" and "exit" commands.

76. 8/30/91 Added "regexp" and "regsub" commands.

77. 9/4/91 Changed "dynamic" field in interpreters to "freeProc" (procedure
address).  This allows for alternative storage managers.
*** POTENTIAL INCOMPATIBILITY ***

78. 9/6/91 Added "index", "length", and "range" options to "string"
command.  Added "lindex", "llength", and "lrange" commands.

79. 9/8/91 Removed "index", "length", "print" and "range" commands.
"Print" is redundant with "puts", but less general, and the other
commands are replaced with the new commands described in change 78
above.
*** POTENTIAL INCOMPATIBILITY ***

80. 9/8/91 Changed history revision to occur even when history command
is nested;  needed in order to allow "history" to be invoked from
"unknown" procedure.

81. 9/13/91 Changed "panic" not to use vfprintf (it's uglier and less
general now, but makes it easier to run Tcl on systems that don't
have vfprintf).  Also changed "strerror" not to redeclare sys_errlist.

82. 9/19/91 Lots of changes to improve portability to different UNIX
systems, including addition of "config" script to adapt Tcl to the
configuration of the system it's being compiled on.

83. 9/22/91 Added "pwd" command.

84. 9/22/91 Renamed manual pages so that their filenames are no more
than 14 characters in length, moved to "doc" subdirectory.

85. 9/24/91 Redid manual entries so they contain the supplemental
macros that they need;  can just print with "troff -man" or "man"
now.

86. 9/26/91 Created initial version of script library, including
a version of "unknown" that does auto-loading, auto-execution, and
abbreviation expansion.  This library is used by tclTest
automatically.  See the "library" manual entry for details.

----------------- Released version 6.0, 9/26/91 ------------------

87. 9/30/91 Made "string tolower" and "string toupper" check case
before converting:  on some systems, "tolower" and "toupper" assume
that character already has particular case.

88. 9/30/91 Fixed bug in Tcl_SetResult:  wasn't always setting freeProc
correctly when called with NULL value.  This tended to cause memory
allocation errors later.

89. 10/3/91 Added "upvar" command.

90. 10/4/91 Changed "format" so that internally it converts %D to %ld,
%U to %lu, %O to %lo, and %F to %f.  This eliminates some compatibility
problems on some machines without affecting behavior.

91. 10/10/91 Fixed bug in "regsub" that caused core dumps with the -all
option when the last match wasn't at the end of the string.

92. 10/17/91 Fixed problems with backslash sequences:  \r support was
incomplete and \f and \v weren't supported at all.

93. 10/24/91 Added Tcl_InitHistory procedure.

94. 10/24/91 Changed "regexp" to store "-1 -1" in subMatchVars that
don't match, rather than returning an error.

95. 10/27/91 Modified "regexp" to return actual strings in matchVar
and subMatchVars instead of indices.  Added "-indices" switch to cause
indices to be returned.
*** POTENTIAL INCOMPATIBILITY ***

96. 10/27/91 Fixed bug in "scan" where it used hardwired constants for
sizes of floats and doubles instead of using "sizeof".

97. 10/31/91 Fixed bug in tclParse.c where parse-related error messages
weren't being storage-managed correctly, causing spurious free's.

98. 10/31/91 Form feed and vertical tab characters are now considered
to be space characters by the parser.

99. 10/31/91 Added TCL_LEAVE_ERR_MSG flag to procedures like Tcl_SetVar.

100. 11/7/91 Fixed bug in "case" where "in" argument couldn't be omitted
if all case branches were embedded in a single list.

101. 11/7/91 Switched to use "pid_t" and "uid_t" and other official
POSIC types and function prototypes.

----------------- Released version 6.1, 11/7/91 ------------------

102. 12/2/91 Modified Tcl_ScanElement and Tcl_ConvertElement in several
ways.  First, allowed caller to request that only backslashes be used
(no braces).  Second, made Tcl_ConvertElement more aggressive in using
backslashes for braces and quotes.

103. 12/5/91 Added "type", "lstat", and "readlink" options to "file"
command, plus added new "type" element to output of "stat" and "lstat"
options.

104. 12/10/91 Manual entries had first lines that caused "man" program
to try weird preprocessor.  Added blank comment lines to fix problem.

105. 12/16/91 Fixed a few bugs in auto_mkindex proc:  wasn't handling
errors properly, and hadn't been upgraded for new "regexp" syntax.

106. 1/2/92 Fixed bug in "file" command where it didn't properly handle
a file names containing tildes where the indicated user doesn't exist.

107. 1/2/92 Fixed lots of cases in tclUnixStr.c where two different
errno symbols (e.g. EWOULDBLOCK and EAGAIN) have the same number;  Tcl
will only use one of them.

108. 1/2/92 Lots of changes to configuration script to handle many more
systems more gracefully.  E.g. should now detect the bogus strtoul that
comes with AIX and substitute Tcl's own version instead.

----------------- Released version 6.2, 1/10/92 ------------------

109. 1/20/92 Config didn't have code to actually use "uid_t" variable
to set TCL_UIT_T #define.

110. 2/10/92 Tcl_Eval didn't properly reset "numLevels" variable when
too-deep recursion occurred.

111. 2/29/92 Added "on" and "off" to keywords accepted by Tcl_GetBoolean.

112. 3/19/92 Config wasn't installing default version of strtod.c for
systems that don't have one in libc.a.

113. 3/23/92 Fixed bug in tclExpr.c where numbers with leading "."s,
like 0.75, couldn't be properly substituted into expressions with
variable or command substitution.

114. 3/25/92 Fixed bug in tclUnixAZ.c where "gets" command wasn't
checking to make sure that it was able to write the variable OK.

115. 4/16/92 Fixed bug in tclUnixAZ.c where "read" command didn't
compute file size right for device files.

116. 4/23/92 Fixed but in tclCmdMZ.c where "trace vinfo" was overwriting
the trace command.

----------------- Released version 6.3, 5/1/92 ------------------

117. 5/1/92 Added Tcl_GlobalEval.

118. 6/1/92 Changed auto-load facility to source files at global level.

119. 6/8/92 Tcl_ParseVar wasn't always setting termPtr after errors, which
sometimes caused core dumps.

120. 6/21/92 Fixed bug in initialization of regexp pattern cache.  This
bug caused segmentation violations in regexp commands under some conditions.

121. 6/22/92 Changed implementation of "glob" command to eliminate
trailing slashes on directory names:  they confuse some systems.  There
shouldn't be any user-visible changes in functionality except for names
in error messages not having trailing slashes.

122. 7/2/92 Fixed bug that caused 'string match ** ""' to return 0.

123. 7/2/92 Fixed bug in Tcl_CreateCmdBuf where it wasn't initializing
the buffer to an empty string.

124. 7/6/92 Fixed bug in "case" command where it used NULL pattern string
after errors in the "default" clause.

125. 7/25/92 Speeded up auto_load procedure:  don't reread all the index
files unless the path has changed.

126. 8/3/92 Changed tclUnix.h to define MAXPATHLEN from PATH_MAX, not
_POSIX_PATH_MAX.

----------------- Released version 6.4, 8/7/92 ------------------

127. 8/10/92 Changed tclBasic.c so that comment lines can be continued by
putting a backslash before the newline.

128. 8/21/92 Modified "unknown" to allow the source-ing of a file for
an auto-load to trigger other nested auto-loads, as long as there isn't
any recursion on the same command name.

129. 8/25/92 Modified "format" command to allow " " and "+" flags, and
allow flags in any order.

130. 9/14/92 Modified Tcl_ParseVar so that it doesn't actually attempt
to look up the variable if "noEval" mode is in effect in the interpreter
(it just parses the name).  This avoids the errors that used to occur
in statements like "expr {[info exists foo] && $foo}".

131. 9/14/92 Fixed bug in "uplevel" command where it didn't output the
correct error message if a level was specified but no command.

132. 9/14/92 Renamed manual entries to have extensions like .3 and .n,
and added "install" target to Makefile.

133. 9/18/92 Modified "unknown" command to emulate !!, !<num>, and
^<old>^<new> csh history substitutions.

134. 9/21/92 Made the config script cleverer about figuring out which
switches to pass to "nm".

135. 9/23/92 Fixed tclVar.c to be sure to copy flags when growing variables.
Used to forget about traces in progress and make extra recursive calls
on trace procs.

136. 9/28/92 Fixed bug in auto_reset where it was unsetting variables
that might not exist.

137. 10/7/92 Changed "parray" library procedure to print any array
accessible to caller, local or global.

138. 10/15/92 Fixed bug where propagation of new environment variable
values among interpreters took N! time if there exist N interpreters.

139. 10/16/92 Changed auto_reset procedure so that it also deletes any
existing procedures that are in the auto_load index (the assumption is
that they should be re-loaded to get the latest versions).

140. 10/21/92 Fixed bug that caused lists to be incorrectly generated
for elements that contained backslash-newline sequences.

141. 12/9/92 Added support for TCL_LIBRARY environment variable:  use
it as library location if it's present.

142. 12/9/92 Added "info complete" command, Tcl_CommandComplete procedure.

143. 12/16/92 Changed the Makefile to check to make sure "config" has been
run (can't run config directly from the Makefile because it modifies the
Makefile;  thus make has to be run again after running config).

----------------- Released version 6.5, 12/17/92 ------------------

144. 12/21/92 Changed config to look in several places for libc file.

145. 12/23/92 Added "elseif" support to if.  Also, "then", "else", and
"elseif" may no longer be abbreviated.
*** POTENTIAL INCOMPATIBILITY ***

146. 12/28/92 Changed "puts" and "read" to support initial "-nonewline"
switch instead of additional "nonewline" argument.  The old form is
still supported, but it is discouraged and is no longer documented.
Also changed "puts" to make the file argument default to stdout: e.g.
"puts foo" will print foo on standard output.

147. 1/6/93 Fixed bug whereby backslash-newline wasn't working when
typed interactively, or in "info complete".

148. 1/22/93 Fixed bugs in "lreplace" and "linsert" where close
quotes were being lost from last element before replacement or
insertion.

149. 1/29/93 Fixed bug in Tcl_AssembleCmd where it wasn't requiring
a newline at the end of a line before considering a command to be
complete.  The bug caused some very long lines in script files to
be processed as multiple separate commands.

150. 1/29/93 Various changes in Makefile to add more configuration
options, simplify installation, fix bugs (e.g. don't use -f switch
for cp), etc.

151. 1/29/93 Changed "name1" and "name2" identifiers to "part1" and
"part2" to avoid name conflicts with stupid C++ implementations that
use "name1" and "name2" in a reserved way.

152. 2/1/93 Added "putenv" procedure to replace the standard system
version so that it will work correctly with Tcl's environment handling.

----------------- Released version 6.6, 2/5/93 ------------------

153. 2/10/93 Fixed bugs in config script:  missing "endif" in libc loop,
and tried to use strncasecmp.c instead of strcasecmp.c.

154. 2/10/93 Makefile improvements:  added RANLIB variable for easier
Sys-V configuration, added SHELL variable for SGI systems.

----------------- Released version 6.7, 2/11/93 ------------------

153. 2/6/93 Changes in backslash processing:
    - \Cx, \Mx, \CMx, \e sequences no longer special
    - \<newline> also eats up any space after the newline, replacing
      the whole sequence with a single space character
    - Hex sequences like \x24 are now supported, along with ANSI C's \a.
    - "format" no longer does backslash processing on its format string
    - there is no longer any special meaning to a 0 return value from
      Tcl_Backslash
    - unknown backslash sequences, like (e.g. \*), are replaced with
      the following character (e.g. *), instead of just treating the
      backslash as an ordinary character.
*** POTENTIAL INCOMPATIBILITY ***

154. 2/6/93 Updated all copyright notices.  The meaning hasn't changed
at all but the wording does a better job of protecting U.C. from
liability (according to U.C. lawyers, anyway).

155. 2/6/93 Changed "regsub" so that it overwrites the result variable
in all cases, even if there is no match.
*** POTENTIAL INCOMPATIBILITY ***

156. 2/8/93 Added support for XPG3 %n$ conversion specifiers to "format"
command.

157. 2/17/93 Fixed bug in Tcl_Eval where errors due to infinite
recursion could result in core dumps.

158. 2/17/93 Improved the auto-load mechanism to deal gracefully (i.e.
return an error) with a situation where a library file that supposedly
defines a procedure doesn't actually define it.

159. 2/17/93 Renamed Tcl_UnixError procedure to Tcl_PosixError, and
changed errorCode variable usage to use POSIX as keyword instead of
UNIX.
*** POTENTIAL INCOMPATIBILITY ***

160. 2/19/93 Changes to exec and process control:
    - Added support for >>, >&, >>&, |&, <@, >@, and >&@ forms of redirection.
    - When exec puts processes into background, it returns a list of
      their pids as result.
    - Added support for <file, >file, etc. (i.e. no space between
      ">" and file name.
    - Added -keepnewline option.
    - Deleted Tcl_Fork and Tcl_WaitPids procedures (just use fork and
      waitpid instead).
    - Added waitpid compatibility procedure for systems that don't have
      it.
    - Added Tcl_ReapDetachedProcs procedure.
    - Changed "exec" to return an error if there is stderr output, even
      if the command returns a 0 exit status (it's always been documented
      this way, but the implementation wasn't correct).
    - If a process returns a non-zero exit status but doesn't generate
      any diagnostic output, then Tcl generates an error message for it.
*** POTENTIAL INCOMPATIBILITY ***

161. 2/25/93 Fixed two memory-management problems having to do with
managing the old result during variable trace callbacks.

162. 3/1/93 Added dynamic string library:  Tcl_DStringInit, Tcl_DStringAppend,
Tcl_DStringFree, Tcl_DStringResult, etc.

163. 3/1/93 Modified glob command to only return the names of files that
exist, and to only return names ending in "/" if the file is a directory.
*** POTENTIAL INCOMPATIBILITY ***

164. 3/19/93 Modified not to use system calls like "read" directly,
but instead to use special Tcl procedures that retry automatically
if interrupted by signals.

165. 4/3/93 Eliminated "noSep" argument to Tcl_AppendElement, plus
TCL_NO_SPACE flag for Tcl_SetVar and Tcl_SetVar2.
*** POTENTIAL INCOMPATIBILITY ***

166. 4/3/93 Eliminated "flags" and "termPtr" arguments to Tcl_Eval.
*** POTENTIAL INCOMPATIBILITY ***

167. 4/3/93 Changes to expressions:
    - The "expr" command now accepts multiple arguments, which are
      concatenated together with space separators.
    - Integers aren't automatically promoted to floating-point if they
      overflow the word size:  errors are generated instead.
    - Tcl can now handle "NaN" and other special values if the underlying
      library procedures handle them.
    - When printing floating-point numbers, Tcl ensures that there is a "."
      or "e" in the number, so it can't be treated as an integer accidentally.
      The procedure Tcl_PrintDouble is available to provide this function
      in other contexts.  Also, the variable "tcl_precision" can be used
      to set the precision for printing (must be a decimal number giving
      digits of precision).
    - Expressions now support transcendental and other functions, e.g. sin,
      acos, hypot, ceil, and round.  Can add new math functions with
      Tcl_CreateMathFunc().
    - Boolean expressions can now have any of the string values accepted
      by Tcl_GetBoolean, such as "yes" or "no".
*** POTENTIAL INCOMPATIBILITY ***

168. 4/5/93 Changed Tcl_UnsetVar and Tcl_UnsetVar2 to return TCL_OK
or TCL_ERROR instead of 0 or -1.
*** POTENTIAL INCOMPATIBILITY ***

169. 4/5/93 Eliminated Tcl_CmdBuf structure and associated procedures;
can use Tcl_DStrings instead.
*** POTENTIAL INCOMPATIBILITY ***

170. 4/8/93 Changed interface to Tcl_TildeSubst to use a dynamic
string for buffer space.  This makes the procedure re-entrant and
thread-safe, whereas it wasn't before.
*** POTENTIAL INCOMPATIBILITY ***

171. 4/14/93 Eliminated tclHash.h, and moved everything from it to
tcl.h
*** POTENTIAL INCOMPATIBILITY ***

172. 4/15/93 Eliminated Tcl_InitHistory, made "history" command always
be part of interpreter.
*** POTENTIAL INCOMPATIBILITY ***

173. 4/16/93 Modified "file" command so that "readable" option always
exists, even on machines that don't support symbolic links (always returns
same error as if the file wasn't a symbolic link).

174. 4/26/93 Fixed bugs in "regsub" where ^ patterns didn't get handled
right (pretended not to match when it really did, and looped infinitely
if -all was specified).

175. 4/29/93 Various improvements in the handling of variables:
    - Can create variables and array elements during a read trace.
    - Can delete variables during traces (note: unset traces will be
      invoked when this happens).
    - Can upvar to array elements.
    - Can retarget an upvar to another variable by re-issuing the
      upvar command with a different "other" variable.

176. 5/3/93 Added Tcl_GetCommandInfo, which returns info about a Tcl
command such as whether it exists and its ClientData.  Also added
Tcl_SetCommandInfo, which allows any of this information to be modified
and also allows a command's delete procedure to have a different
ClientData value than its command procedure.

177. 5/5/93 Added Tcl_RegExpMatch procedure.

178. 5/6/93 Fixed bug in "scan" where it didn't properly handle
%% conversion specifiers.  Also changed "scan" to use Tcl_PrintDouble
for printing real values.

179. 5/7/93 Added "-exact", "-glob", and "-regexp" options to "lsearch"
command to allow different kinds of pattern matching.

180. 5/7/93 Added many new switches to "lsort" to control the sorting
process: "-ascii", "-integer", "-real", "-command", "-increasing",
and "-decreasing".

181. 5/10/93 Changes to file I/O:
    - Modified "open" command to support a list of POSIX access flags
      like {WRONLY CREAT TRUNC} in addition to current fopen-style
      access modes.  Also added "permissions" argument to set permissions
      of newly-created files.
    - Fixed Scott Bolte's bug (can close stdin etc. in application and
      then re-open them with Tcl commands).
    - Exported access to Tcl's file table with new procedures Tcl_EnterFile
      and Tcl_GetOpenFile.

182. 5/15/93 Added new "pid" command, which can be used to retrieve
either the current process id or a list of the process ids in a
pipeline opened with "open |..."

183. 6/3/93 Changed to use GNU autoconfig for configuration instead of
the home-brew "config" script.  Also made many other configuration-related
changes, such as using <unistd.h> instead of explicitly declaring system
calls in tclUnix.h.

184. 6/4/93 Fixed bug where core-dumps could occur if a procedure
redefined itself (the memory for the procedure's body could get
reallocated in the middle of evaluating the body);  implemented
simple reference count mechanism.

185. 6/5/93 Changed tclIndex file format in two ways:  (a) it's now
eval-ed instead of parsed, which makes it 3-4x faster; (b) the entries
in auto_index are now commands to evaluate, which allows commands to
be loaded in different ways such as dynamic-loading of C code.  The
old tclIndex file format is still supported.

186. 6/7/93 Eliminated tclTest program, added new "tclsh" program
that is more like wish (allows script files to be invoked automatically
using "#!/usr/local/bin/tclsh", makes arguments available to script,
etc.).  Added support for Tcl_AppInit plus default version;  this
allows new Tcl applications to be created without modifying the
main program for tclsh.

187. 6/7/93 Fixed bug in TclWordEnd that kept backslash-newline from
working correctly in some cases during interactive input.

188. 6/9/93 Added Tcl_LinkVar and related procedures, which automatically
keep a Tcl variable in sync with a C variable.

189. 6/16/93 Increased maximum nesting depth from 100 to 1000.

190. 6/16/93 Modified "trace var" command so that error messages from
within traces are returned properly as the result of the variable
access, instead of the generic "access disallowed by trace command"
message.

191. 6/16/93 Added Tcl_CallWhenDeleted to provide callbacks when an
interpreter is deleted (same functionality as Tcl_WatchInterp, which
used to exist in versions before 6.0).

193. 6/16/93 Added "-code" argument to "return" command;  it's there
primarily for completeness, so that procedures implementing control
constructs can reflect exceptional conditions back to their callers.

194. 6/16/93 Split up Tcl.n to make separate manual entries for each
Tcl command.  Tcl.n now contains a summary of the language syntax.

195. 6/17/93 Added new "switch" command to replace "case": allows
alternate forms of pattern matching (exact, glob, regexp), replaces
pattern lists with single patterns (but you can use "-" bodies to
share one body among several patterns), eliminates "in" noise word.
"Case" command is now obsolete.

196. 6/17/93 Changed the "exec", "glob", "regexp", and "regsub" commands
to include a "--" switch.  All initial arguments starting with "-" are now
treated as switches unless a "--" switch is present to end the list.
*** POTENTIAL INCOMPATIBILITY ***

197. 6/17/93 Changed auto-exec so that the subprocess gets stdin, stdout,
and stderr from the parent.  This allows truly interactive sub-processes
(e.g. vi) to be auto-exec'ed from a tcl shell command line.

198. 6/18/93 Added patchlevel.h, for use in coordinating future patch
releases, and also added "info patchlevel" command to make the patch
level available to Tcl scripts.

199. 6/19/93 Modified "glob" command so that a leading "//" in a name
gets left as is (this is needed for systems like Apollos where "//" is
the super-root;  Tcl used to collapse the two slashes into a single
slash).

200. 7/7/93 Added Tcl_SetRecursionLimit procedure so that the maximum
allowable nesting depth can be controlled for an interpreter from C.

----------------- Released version 7.0 Beta 1, 7/9/93 ------------------

201. 7/12/93 Modified Tcl_GetInt and tclExpr.c so that full-precision
unsigned integers can be specified without overflow errors.

202. 7/12/93 Configuration changes:  eliminate leading blank line in
configure script;  provide separate targets in Makefile for installing
binary and non-binary information; check for size_t and a few other
potentially missing typedefs; don't put tclAppInit.o into libtcl.a;
better checks for matherr support.

203. 7/14/93 Changed tclExpr.c to check the termination pointer before
errno after strtod calls, to avoid problems with some versions of
strtod that set errno in unexpected ways.

204. 7/16/93 Changed "scan" command to be more ANSI-conformant:
eliminated %F, %D, etc., added code to ignore "l", "h", and "L"
modifiers but always convert %e, %f, and %g with implicit "l";
also added support for %u and %i.  Also changed "format" command
to eliminate %D, %U, %O, and add %i.
*** POTENTIAL INCOMPATIBILITY ***

205. 7/17/93 Changed "uplevel" and "upvar" so that they can be used
from global level to global level:  this used to generate an error.

206. 7/19/93 Renamed "setenv", "putenv", and "unsetenv" procedures
to avoid conflicts with system procedures with the same names.  If
you want Tcl's procedures to override the system procedures, do it
in the Makefile (instructions are in the Makefile).
*** POTENTIAL INCOMPATIBILITY ***

----------------- Released version 7.0 Beta 2, 7/21/93 ------------------

207. 7/21/93 Fixed bug in tclVar.c where freed memory was accidentally
used if a procedure returned an element of a local array.

208. 7/22/93 Fixed bug in "unknown" where it didn't properly handle
errors occurring in the "auto_load" procedure, leaving its state
inconsistent.

209. 7/23/93 Changed exec's ">2" redirection operator to "2>" for
consistency with sh.  This is incompatible with earlier beta releases
of 7.0 but not with pre-7.0 releases, which didn't support either
operator.

210. 7/28/93 Changed backslash-newline handling so that the resulting
space character *is* treated as a word separator unless the backslash
sequence is in quotes or braces.  This is incompatible with 7.0b1
and 7.0b2 but is more compatible with pre-7.0 versions that the b1
and b2 releases were.

211. 7/28/93 Eliminated Tcl_LinkedVarWritable, added TCL_LINK_READ_ONLY to
Tcl_LinkVar to accomplish same purpose.  This change is incompatible
with earlier beta releases, but not with releases before Tcl 7.0.

212. 7/29/93 Renamed regexp C functions so they won't clash with POSIX
regexp functions that use the same name.

213. 8/3/93 Added "-errorinfo" and "-errorcode" options to "return"
command: these allow for much better handling of the errorInfo
and errorCode variables in some cases.

214. 8/12/93 Changed "expr" so that % always returns a remainder with
the same sign as the divisor and absolute value smaller than the
divisor.

215. 8/14/93 Turned off auto-exec in "unknown" unless the command
was typed interactively.  This means you must use "exec" when
invoking subprocesses, unless it's a command that's typed interactively.
*** POTENTIAL INCOMPATIBILITY ***

216. 8/14/93 Added support for tcl_prompt1 and tcl_prompt2 variables
to tclMain.c:  makes prompts user-settable.

217. 8/14/93 Added asynchronous handlers (Tcl_AsyncCreate etc.) so
that signals can be taken cleanly by Tcl applications.

218. 8/16/93 Moved information about open files from the interpreter
structure to global variables so that a file can be opened in one
interpreter and read or written in another.

219. 8/16/93 Removed ENV_FLAGS from Makefile, so that there's no
official support for overriding setenv, unsetenv, and putenv.

220. 8/20/93 Various configuration improvements:  coerce chars
to unsigned chars before using macros like isspace;  source ~/.tclshrc
file during initialization if it exists and program is running
interactively;  allow there to be directories in auto_path that don't
exist or don't have tclIndex files (ignore them); added Tcl_Init
procedure and changed Tcl_AppInit to call it.

221. 8/21/93 Fixed bug in expr where "+", "-", and " " were all
getting treated as integers with value 0.

222. 8/26/93 Added "tcl_interactive" variable to tclsh.

223. 8/27/93 Added procedure Tcl_FilePermissions to return whether a
given file can be read or written or both.  Modified Tcl_EnterFile
to take a permissions mask rather than separate read and write arguments.

224. 8/28/93 Fixed performance bug in "glob" command (unnecessary call
to "access" for each file caused a 5-10x slow-down for big directories).

----------------- Released version 7.0 Beta 3, 8/28/93 ------------------

225. 9/9/93 Renamed regexp.h to tclRegexp.h to avoid conflicts with system
include file by same name.

226. 9/9/93 Added Tcl_DontCallWhenDeleted.

227. 9/16/93 Changed not to call exit C procedure directly;  instead
always invoke "exit" Tcl command so that application can redefine the
command to do additional cleanup.

228. 9/17/93 Changed auto-exec to handle names that contain slashes
(i.e. don't use PATH for them).

229. 9/23/93 Fixed bug in "read" and "gets" commands where they didn't
clear EOF conditions.

----------------- Released version 7.0, 9/29/93 ------------------

230. 10/7/93 "Scan" command wasn't properly aligning things in memory,
so segmentation faults could arise under some circumstances.

231. 10/7/93 Fixed bug in Tcl_ConvertElement where it forgot to
backslash leading curly brace when creating lists.

232. 10/7/93 Eliminated dependency of tclMain.c on tclInt.h and
tclUnix.h, so that people can copy the file out of the Tcl source
directory to make modified private versions.

233. 10/8/93 Fixed bug in auto-loader that reversed the priority order
of entries in auto_path for new-style index files.  Now things are
back to the way they were before 3.0:  first in auto_path is always
highest priority.

234. 10/13/93 Fixed bug where Tcl_CommandComplete didn't recognize
comments and treat them as such.  Thus if you typed the line
    # {
interactively, Tcl would think that the command wasn't complete and
wait for more input before evaluating the script.

235. 10/14/93 Fixed bug where "regsub" didn't set the output variable
if the input string was empty.

236. 10/23/93 Fixed bug where Tcl_CreatePipeline didn't close off enough
file descriptors in child processes, causing children not to exit
properly in some cases.

237. 10/28/93 Changed "list" and "concat" commands not to generate
errors if given zero arguments, but instead to just return an empty
string.

----------------- Released version 7.1, 11/4/93 ------------------

Note: there is no 7.2 release.  It was flawed and was thus withdrawn
shortly after it was released.

238. 11/10/93 TclMain.c didn't compile on some systems because of
R_OK in call to "access".  Changed to eliminate call to "access".

----------------- Released version 7.3, 11/26/93 ------------------

239. 11/6/93 Modified "lindex", "linsert", "lrange", and "lreplace"
so that "end" can be specified as an index.

240. 11/6/93 Modified "append" and "lappend" to allow only two
words total (i.e., nothing to append) without generating an error.

241. 12/2/93 Changed to use EAGAIN as the errno for non-blocking
I/O instead of EWOULDBLOCK:  this should fix problem where non-blocking
I/O didn't work correctly on System-V systems.

242. 12/22/93 Fixed bug in expressions where cancelled evaluation
wasn't always working correctly (e.g. "set one 1; eval {1 || 1/$one}"
failed with a divide by zero error).

243. 1/6/94 Changed TCL_VOLATILE definition from -1 to the address of
a dummy procedure Tcl_Volatile, since -1 causes portability problems on
some machines (e.g., Crays).

244. 2/4/94 Added support for unary plus.

245. 2/17/94 Changed Tcl_RecordAndEval and "history" command to
call Tcl_GlobalEval instead of Tcl_Eval.  Otherwise, invocation of
these facilities in nested procedures can cause unwanted results.

246. 2/17/94 Fixed bug in tclExpr.c where an expression such as
"expr {"12398712938788234-1298379" != ""}" triggers an integer
overflow error for the number in quotes, even though it isn't really
a proper integer anyway.

247. 2/19/94 Added new procedure Tcl_DStringGetResult to move result
from interpreter to a dynamic string.

248. 2/19/94 Fixed bug in Tcl_DStringResult that caused it to overwrite
the contents of a static result in some situations.  This can cause
bizarre errors such as variables suddenly having empty values.

249. 2/21/94 Fixed bug in Tcl_AppendElement, Tcl_DStringAppendElement,
and the "lappend" command that caused improper omission of a separator
space in some cases.  For example, the script
    set x "abc{"; lappend x "def"
used to return the result "abc{def" instead of "abc{ def".

250. 3/3/94 Tcl_ConvertElement was outputting empty elements as \0 if
TCL_DONT_USE_BRACES was set.  This depends on old pre-7.0 meaning of
\0, which is no longer in effect, so it didn't really work.  Changed
to output empty elements as {} always.

251. 3/3/94 Renamed Tcl_DStringTrunc to Tcl_DStringSetLength and extended
it so that it can be used to lengthen a string as well as shorten it.
Tcl_DStringTrunc is defined as a macro for backward compatibility, but
it is deprecated.

252. 3/3/94 Added Tcl_AllowExceptions procedure.

253. 3/13/94 Fixed bug in Tcl_FormatCmd that could cause "format"
to mis-behave on 64-bit Big-Endian machines.

254. 3/13/94 Changed to use vfork instead of fork on systems where
vfork exists.

255. 3/23/94 Fixed bug in expressions where ?: didn't associate
right-to-left as they should.

256. 4/3/94 Fixed "exec" to flush any files used in >@ or >&@
redirection in exec, so that data buffered for them is written
before any new data added by the subprocess.

257. 4/3/94 Added "subst" command.

258. 5/20/94 The tclsh main program is now called Tcl_Main;  tclAppInit.c
has a "main" procedure that calls Tcl_Main.  This makes it easier to use
Tcl with C++ programs, which need their own main programs, and it also
allows an application to prefilter the argument list before calling
Tcl_Main.
*** POTENTIAL INCOMPATIBILITY ***

259. 6/6/94 Fixed bug in procedure returns where the errorInfo variable
could get truncated if an unset trace was invoked as part of returning
from the procedure.

260. 6/13/94 Added "wordstart" and "wordend" options to "string" command.

261. 6/27/94 Fixed bug in expressions where they didn't properly cancel
the evaluation of math functions in &&, ||, and ?:.

262. 7/11/94 Incorrect boolean values, like "ogle", weren't being
handled properly.

263. 7/15/94 Added Tcl_RegExpCompile, Tcl_RegExpExec, and Tcl_RegExpRange,
which provide lower-level access to regular expression pattern matching.

264. 7/22/94 Fixed bug in "glob" command where "glob -nocomplain ~bad_user"
would complain about a missing user.  Now it doesn't complain anymore.

265. 8/4/94 Fixed bug with linked variables where they didn't behave
correctly when accessed via upvars.

266. 8/17/94 Fixed bug in Tcl_EvalFile where it didn't clear interp->result.

267. 8/31/94 Modified "open" command so that errors in exec-ing
subprocesses are returned by the open immediately, rather than
being delayed until the "close" is executed.

268. 9/9/94 Modified "expr" command to generate errors for integer
overflow (includes addition, subtraction, negation, multiplication,
division).

269. 9/23/94 Modified "regsub" to return a count of the number of
matches and replacements, rather than 0/1.

279. 10/4/94 Added new features to "array" command:
    - added "get" and "set" commands for easy conversion between arrays
      and lists.
    - added "exists" command to see if a variable is an array, changed
      "names" and "size" commands to treat a non-existent array (or scalar
      variable) just like an empty one.
    - added pattern option to "names" command.

280. 10/6/94 Modified Tcl_SetVar2 so that read traces on variables get
called during append operations.

281. 10/20/94 Fixed bug in "read" command where reading from stdin
required two control-D's to stop the reading.

282. 11/3/94 Changed "expr" command to use longs for division just like
all other expr operators;  it previously used ints for division.

283. 11/4/94 Fixed bugs in "unknown" procedure:  it wasn't properly
handling exception returns from commands that were executed after
being auto-loaded.

----------------- Released version 7.4b1, 12/23/94 ------------------

284. 12/26/94 Fixed "install" target in Makefile (couldn't always
find install program).

285. 12/26/94 Added strcncasecmp procedure to compat directory.

286. 1/3/95 Fixed all procedure calls to explicitly cast arguments:
implicit conversions from prototypes (especially integer->double)
don't work when compiling under non-ANSI compilers.  Tcl is now clean
under gcc -Wconversion.

287. 1/4/95 Fixed problem in Tcl_ArrayCmd where same name was used for
both a label and a variable;  caused problems on several older compilers,
making array command misbehave and causing many errors in Tcl test suite.

----------------- Released version 7.4b2, 1/12/95 ------------------

288. 2/9/95 Modified Tcl_CreateCommand to return a token, and added
Tcl_GetCommandName procedure.  Together, these procedures make it possible
to track renames of a command.

289. 2/13/95 Fixed bug in expr where "089" was interpreted as a
floating-point number rather than a bogus octal number.
*** POTENTIAL INCOMPATIBILITY ***

290. 2/14/95 Added code to Tcl_GetInt and Tcl_GetDouble to check for
overflows when reading in numbers.

291. 2/18/95 Changed "array set" to stop after first error, rather than
continuing after error.

292. 2/20/95 Upgraded to use autoconf version 2.2.

293. 2/20/95 Fixed core dump that could occur in "scan" command if a
close bracket was omitted.

294. 2/27/95 Changed Makefile to always use install-sh for installations:
there's just too much variation among "install" system programs, which
makes installation flakey.

----------------- Released version 7.4b3, 3/24/95 ------------------

3/25/95 (bug fix) Changed "install" to "./install" in Makefile so that
"make install" will work even when "." isn't in the search path.

3/29/95 (bug fix) Fixed bug where the auto-loading mechanism wasn't
protecting the values of the errorCode and errorInfo variables.

3/29/95 (new feature) Added optional pattern argument to "parray" procedure.

3/29/95 (bug fix) Made the full functionality of
    "return -code ... -errorcode ..."
work not just inside procedures, but also in sourced files and at
top level.

4/6/95 (new feature) Added "pattern" option to "array names" command.

4/18/95 (bug fix) Fixed bug in parser where it didn't allow backslash-newline
immediately after an argument in braces or quotes.

4/19/95 (new feature) Added tcl_library variable, which application can
set to override default library directory.

4/30/95 (bug fix) During trace callbacks for array elements, the variable
name used in the original reference would be temporarily modified to
separate the array name and element name;  if the trace callback used
the same name string, it would get the wrong name (the array name without
element).  Fixed to restore the variable name before making trace
callbacks.

4/30/95 (new feature) Added -nobackslashes, -nocommands, and -novariables
switches to "subst" command.

5/4/95 (new feature) Added TCL_EVAL_GLOBAL flag to Tcl_RecordAndEval.

5/5/95 (bug fix)  Format command would overrun memory when printing
integers with very large precision, as in "format %.1000d 0".

5/5/95 (portability improvement) Changed to use BSDgettimeofday on
IRIX machines, to avoid compilation problems with the gettimeofday
declaration.

5/6/95 (bug fix) Changed manual entries to use the standard .TH
macro instead of a custom .HS macro;  the .HS macro confuses index
generators like makewhatis.

5/9/95 (bug fix) Modified configure script to check for Solaris bug
that makes vfork unreliable (core dumps result if vforked child
changes a signal handler);  will use fork instead of vfork if the
bug is present.

6/5/95 (bug fix) Modified "lsort" command to disallow recursive calls
to lsort from a comparison function.  This is needed because qsort
is not reentrant.

6/5/95 (bug fix) Undid change 243 above:  changed TCL_VOLATILE and
TCL_DYNAMIC back to integer constants rather than procedure addresses.
This was needed because procedure addresses can have multiple values
under some dynamic loading systems (e.g. SunOS 4.1 and Windows).

6/8/95 (feature change) Modified interface to Tcl_Main to pass in the
address of the application-specific initialization procedure.
Tcl_AppInit is no longer hardwired into Tcl_Main.  This is needed
in order to make Tcl a shared library. 

6/8/95 (feature change) Modified Makefile so that the installed versions
of tclsh and libtcl.a have version number in them (e.g. tclsh7.4 and
libtcl7.4.a) and the library directory name also has an embedded version
number (e.g., /usr/local/lib/tcl7.4).  This should make it easier for
Tcl 7.4 to coexist with earlier versions.

----------------- Released version 7.4b4, 6/16/95 ------------------

6/19/95 (bug fix) Fixed bugs in tclCkalloc.c that caused core dumps
if TCL_MEM_DEBUG was enabled on word-addressed machines such as Crays.

6/21/95 (feature removal) Removed overflow checks for integer arithmetic:
they just cause too much trouble (e.g. for random  number generators).

6/28/95 (new features) Added tcl_patchLevel and tcl_version variables,
for consistency with Tk.

6/29/95 (bug fix) Fixed problem in Tcl_Eval where it didn't record
the right termination character if a script ended with a comment.  This
caused erroneous output for the following command, among others:
puts "[
expr 1+1
# duh!
]"

6/29/95 (message change) Changed the error message for ECHILD slightly
to provide a hint about why the problem is occurring.

----------------- Released version 7.4, 7/1/95 ------------------

7/18/95 (bug fix) Changed "lreplace" so that nothing is deleted if
the last index is less than the first index or if the last index
is < 0.

7/18/95 (bug fix) Fixed bugs with backslashes in comments:
Tcl_CommandComplete (and "info complete") didn't properly handle
strings ending in backslash-newline, and neither Tcl_CommandComplete
nor the Tcl parser handled other backslash sequences right, such
as two backslashes before a newline.

7/19/95 (bug fix) Modified Tcl_DeleteCommand to delete the hash table
entry for the command before invoking its callback.  This is needed in
order to deal with reentrancy.

7/22/95 (bug fix) "exec" wasn't reaping processes correctly after
certain errors (e.g. if the name of the executable was bogus, as
in "exec foobar").

7/27/95 (bug fix) Makefile.in wasn't using the LIBS variable provided
by the "configure" script.  This caused problems on some SCO systems.

7/27/95 (bug fix) The version of strtod in fixstrtod.c didn't properly
handle the case where endPtr == NULL.

----------------- Released patch 7.4p1, 7/29/95 -----------------------

8/4/95 (bug fix) C-level trace callbacks for variables were sometimes
receiving the PART1_NOT_PARSED flag, which could cause errors in
subsequent Tcl library calls using the flags. (JO)

8/4/95 (bug fix) Calls to toupper and tolower weren't using the
UCHAR macros, which caused trouble in non-U.S. locales. (JO)

8/10/95 (new feature) Added the "load" command for dynamic loading of
binary packages, and the Tcl_PackageInitProc prototype for package
initialization procedures. (JO)

8/23/95 (new features) Added "info sharedlibextension" and
"info nameofexecutable" commands, plus Tcl_FindExtension procedure. (JO)

8/25/95 (bug fix) If the target of an "upvar" was non-existent but
had traces set, the traces were silently lost.  Change to generate
an error instead. (JO)

8/25/95 (bug fix) Undid change from 7/19, so that commands can stay
around while their deletion callbacks execute.  Added lots of code to
handle all of the reentrancy problems that this opens up. (JO)

8/25/95 (bug fix) Fixed core dump that could occur in TclDeleteVars
if there was an upvar from one entry in the table to the next entry
in the same table. (JO)

8/28/95 (bug fix) Exec wasn't handling bad user names properly, as
in "exec ~bogus_user/foo". (JO)

8/29/95 (bug fixes) Changed backslash-newline handling to correct two
problems:
    - Only spaces and tabs following the backslash-newline are now
      absorbed as part of the backslash-newline.  Newlinew are no
      longer absorbed (add another backslash if you want to absorb
      another newline).
    - TclWordEnd returns the character just before the backslash in
      the sequence as the end of the sequence;  it used to not consider
      the backslash-newline as a word separator. (JO)

8/31/95 (new feature) Changed man page installation (with "mkLinks"
script) to create additional links for manual pages corresponding to
each of the procedure and command names described in the pages. (JO)

9/10/95 Reorganized Tcl sources for Windows and Mac ports.  All sources
are now in subdirectories:  "generic" contains sources that work on all
platforms, "windows", "mac", and "unix" directories contain platform-
specific sources.  Some UNIX sources are also used on other platforms. (SS)

9/10/95 (feature change) Eliminated exported global variables (they
don't work with Windows DLLs).  Replaced tcl_AsyncReady and
tcl_FileCloseProc with procedures Tcl_AsyncReady() and
Tcl_SetFileCloseProc().  Replaced C variable tcl_RcFileName with
a Tcl variable tcl_rcFileName. (SS)
*** POTENTIAL INCOMPATIBILITY ***

9/11/95 (new feature) Added procedure Tcl_SetPanicProc to override
the default implementation of "panic". (SS)

9/11/95 (new feature) Added "interp" command to allow creation of
new interpreters and execution of untrusted scripts.  Added many new
procedures, such as Tcl_CreateSlave, Tcl_CreateAlias,and Tcl_MakeSafe,
to provide C-level access to the interpreter facility. This mechanism
now provides almost all of the generic functions of Borenstein's and
Rose's Safe-Tcl (but not any Tk or email-related stuff).  (JL)

9/11/95 (feature change) Changed file management so that files are
no longer shared between interpreters:  a file cannot normally be
referenced in one interpreter if it was opened in another.  This
feature is needed to support safe interpreters.  Added Tcl_ShareHandle()
procedure for allowing files to be shared, and added "interp" argument
to Tcl_FilePermissions procedure.
*** POTENTIAL INCOMPATIBILITY ***

9/11/95 (new feature) Added "AssocData" mechanism, whereby extensions
can associate their own data with an interpreter and get called back
when the interpreter is deleted.  This is visible at C level via the
procedures Tcl_SetAssocData and Tcl_GetAssocData.  (JL)

9/11/95 (new feature) Added Tcl_ErrnoMsg to translate an errno value
into a human-readable string.  This is now used instead of calling
strerror because strerror mesages vary dramatically from platform
to platform, which messes up Tcl tests.  Tcl_ErrnoMsg uses the standard
POSIX messages for all the common signals, and calls strerror for
signals it doesn't understand.

----------------- Released patch 7.5p2, 9/15/95 -----------------------

----------------- Released 7.5a1, 9/15/95 -----------------------

9/22/95 (bug fix) Changed auto_mkindex to create tclIndex files that
handle directories whose paths might contain spaces. (RJ)

9/27/95 (bug fix) The "format" command didn't check for huge or negative
width specifiers, which could cause core dumps. (JO)

9/27/95 (bug fix) Core dumps could occur if an interactive command typed
to tclsh returned a very long result for tclsh to print out.  The bug is
actually in printf (in Solaris 2.3 and 2.4, at least);  switched to use
puts instead.  (JO)

9/28/95 (bug fix) Changed makefile.bc to eliminate a false dependency
for tcl1675.dll on the Borland run time library. (SS)

9/28/95 (bug fix) Fixed tcl75.dll so it looks for tcl1675.dll instead
of tcl16.dll. (SS)

9/28/95 (bug fix) Tcl was not correctly detecting the difference
between Win32s and Windows '95. (SS)

9/28/95 (bug fix) "exec" was not passing environment changes to child
processes under Windows. (SS)

9/28/95 (bug fix) Changed Tcl to ensure that open files are not passed
to child processes under Windows. (SS)

9/28/95 (bug fix) Fixed Windows '95 and NT versions of exec so it can
handle both console and windows apps.   (SS)

9/28/95 (bug fix) Fixed Windows version of exec so it no longer leaves
temp files lying around.  Also changed it so the temp files are
created in the appropriate system dependent temp directory. (SS)

9/28/95 (bug fix) Eliminated source dependency on the Win32s Universal
Thunk header file, since it is not bundled with VC++. (SS)

9/28/95 (bug fix) Under Windows, Tcl now constructs the HOME
environment variable from HOMEPATH and HOMEDRIVE when HOME is not
already set. (SS)

9/28/95 (bug fix) Added support for "info nameofexecutable" and "info
sharedlibextension" to the Windows version. (SS)

9/28/95 (bug fix) Changed tclsh to correctly parse command line
arguments so that backslashes are preserved under Windows. (SS)

9/29/95 (bug fix) Tcl 7.5a1 treated either return or newline as end
of line in "gets", which caused lines ending in CRLF to be treated as
two separate lines.  Changed to allow only character as end-of-line:
carriage return on Macs, newline elsewhere. (JO)

9/29/95 (new feature) Changed to install "configInfo" file in same
directory as library scripts.  It didn't used to get installed. (JO)

9/29/95 (bug fix) Tcl was not converting Win32 errors into POSIX
errors under some circumstances. (SS)

10/2/95 (bug fix) Safe interpreters no longer get initialized with
a call to Tcl_Init(). (JL)

10/1/95 (new feature) Added "tcl_platform" global variable to provide
environment information such as the instruction set and operating
system. (JO)

10/1/95 (bug fix) "exec" command wasn't always generating the
"child process exited abnormally" message when it should have.  (JO)

10/2/95 (bug fix) Changed "mkLinks.tcl" so that the scripts it generates
won't create links that overwrite original manual entries (there was
a problem where pack-old.n was overwriting pack.n).  (JO)

10/2/95 (feature change) Changed to use -ldl for dynamic loading under
Linux if it is available, but fall back to -ldld if it isn't.  (JO)

10/2/95 (bug fix) File sharing was causing refcounts to reach 0
prematurely for stdin, stdout and stderr, under some circumstances. (JL)

10/2/95 (platform support) Added support for Visual C++ compiler on
Windows, Windows '95 and Windows NT, code donated by Gordon Chaffee. (JL)

10/3/95 (bug fix) Tcl now frees any libraries that it loads before it
exits. (SS)

10/03/95 (bug fix) Fixed bug in Macintosh ls command where the -l
and -C options would fail in anything but the HOME directory. (RJ)

----------------- Released 7.5a2, 10/6/95 -----------------------

10/10/95 (bug fix) "file dirnam /." was returning ":" on UNIX instead
of "/". (JO)

10/13/95 (bug fix) Eliminated dependency on MKS toolkit for generating
the tcl.def file from Borland object files. (SS)

10/17/95 (new features) Moved the event loop from Tcl to Tk, made major
revisions along the way:
    - New Tcl commands:  after, update, vwait (replaces "tkwait variable").
    - "tkerror" is now replaced with "bgerror".
    - The following procedures are similar to their old Tk counterparts:
      Tcl_DoOneEvent, Tcl_Sleep, Tcl_DoWhenIdle, Tcl_CancelIdleCall,
      Tcl_CreateFileHandler, Tcl_DeleteFileHandler, Tcl_CreateTimerHandler,
      Tcl_DeleteTimerHandler, Tcl_BackgroundError.
    - Revised notifier, add new concept of "event source" with the following
      procedures:  Tcl_CreateEventSource, Tcl_DeleteEventSource,
      Tcl_WatchFile, Tcl_SetMaxBlockTime, Tcl_FileReady, Tcl_QueueEvent,
      Tcl_WaitForEvent. (JO)

10/31/95 (new features) Implemented cross platform file name support to make
it easier to write cross platform scripts.  Tcl now understands 4 file naming
conventions: Windows (both DOS and UNC), Mac, Unix, and Network.  The network
convention is a new naming mechanism that can be used to paths in a platform
independent fashion.  See the "file" command manual page for more details.
The primary interfaces changes are:
    - All Tcl commands that expect a file name now accept both network and
      native form.
    - Two new "file" subcommands, "nativename" and "networkname", provide a
      way to convert between network and native form.
    - Renamed Tcl_TildeSubst to Tcl_TranslateFileName, and changed it so that
      it always returns a filename in native form.  Tcl_TildeSubst is defined
      as a macro for backward compatibility, but it is deprecated. (SS)

11/5/95 (new feature) Made "tkerror" and "bgerror" synonyms, so that
either name can be used to manipulate the command (provides temporary
backward compatibility for existing scripts that use tkerror). (JO)

11/5/95 (new feature) Added exit handlers and new C procedures
Tcl_CreateExitHandler, Tcl_DeleteExitHandler, and Tcl_Exit. (JO)

11/6/95 (new feature) Added pid command for Macintosh version of
Tcl (it didn't previously exist on the Mac). (RJ)

11/7/95 (new feature) New generic IO facility and support for IO to
files, pipes and sockets based on a common buffering scheme. Support
for asynchronous (non-blocking) IO and for event driver IO. Support
for automatic (background) asynchronous flushing and asynchronous
closing of channels. (JL)

11/7/95 (new feature)  Added new commands "fconfigure" and "fblocked"
to support new I/O features such as nonblocking I/O.  Added "socket"
command for creating TCP client and server sockets. (JL).

11/7/95 (new feature) Complete set of C APIs to the new generic IO
facility:
    - Opening channels: Tcl_OpenFileChannel, Tcl_OpenCommandChannel,
      Tcl_OpenTcpClient, Tcl_OpenTcpServer.
    - I/O procedures on channels, which roughly mirror the ANSI C stdio
      library:  Tcl_Read, Tcl_Gets, Tcl_Write, Tcl_Flush, Tcl_Seek,
      Tcl_Tell, Tcl_Close, Tcl_Eof, Tcl_InputBlocked, Tcl_GetChannelOption,
      Tcl_SetChannelOption.
    - Extension mechanism for creating new kinds of channels:
      Tcl_CreateChannel, Tcl_GetChannelInstanceData, Tcl_GetChannelType,
      Tcl_GetChannelName, Tcl_GetChannelFile, Tcl_RegisterChannel,
      Tcl_UnregisterChannel, Tcl_GetChannel.
    - Event-driven I/O on channels: Tcl_CreateChannelHandler,
      Tcl_DeleteChannelHandler. (JL)

11/7/95 (new feature) Channel driver interface specification to allow
new types of channels to be added easily to Tcl. Currently being used
in three drivers - for files, pipes and TCP-based sockets. (JL).

11/7/95 (new feature) interp delete now takes any number of path
names of interpreters to delete, including zero. (JL).

11/8/95 (new feature) implemented 'info hostname' and Tcl_GetHostName
command to get host name of machine on which the Tcl process is running. (JL)

11/9/95 (new feature) Implemented file APIs for access to low level files
on each system. The APIs are: Tcl_CloseFile, Tcl_OpenFile, Tcl_ReadFile,
Tcl_WriteFile and Tcl_SeekFile. Also implemented Tcl_WaitPid which waits
in a system dependent manner for a child process. (JL)

11/9/95 (new feature) Added Tcl_UpdateLinkedVar procedure to force a
Tcl variable to be updated after its C variable changes. (JO)

11/9/95 (bug fix) The glob command has been totally reimplemented so
that it can support different file name conventions.  It now handles
Windows file names (both UNC and drive-relative) properly.  It also
supports nested braces correctly now. (SS)

11/13/95 (bug fix) Fixed Makefile.in so that configure can be run
from a clean directory separate from the Tcl source tree, and compilations
can be performed there. (JO)

11/14/95 (bug fix) Fixed file sharing between interpreters and file
transferring between interpreters to correctly manage the refcount so that
files are closed when the last reference to them is discarded. (JL)

11/14/95 (bug fix) Fixed gettimeofday implementation for the
Macintosh.  This fixes several timing related bugs. (RJ)

11/17/95 (new feature) Added missing support for info nameofexecutable
on the Macintosh. (RJ)

11/17/95 (bug fix) The Tcl variables argc argv and argv0 now return
something reasonable on the Mac.  (RJ)

11/22/95 (new feature) Implemented "auto-detect" mode for end of line
translations. On input, standalone "\r" mean MAC mode, standalone "\n"
mean Unix mode and "\r\n" means Windows mode. On output, the mode is
modified to whatever the platform specific mode for that platform is. (JL)

11/24/95 (feature change) Replaced "configInfo" file with tclConfig.sh,
which is more complete and uses slightly different names.  Also
arranged for tclConfig.sh to be installed in the platform-specific
library directory instead of Tcl's script library directory. (JO)
*** POTENTIAL INCOMPATIBILITY with Tcl 7.5a2, but not with Tcl 7.4 ***

----------------- Released patch 7.4p3, 11/28/95 -----------------------

12/5/95 (new feature) Added Tcl_File facility to support platform-
independent file handles.  Changed all interfaces that used Unix-
style integer fd's to use Tcl_File's instead. (SS)
*** POTENTIAL INCOMPATIBILITY ***

12/5/95 (new feature) Added a new "clock" command to Tcl.  The command
allows you to get the current "clicks" or seconds & allows you to
format or scan human readable time/date strings. (RJ)

12/18/95 (new feature) Moved Tk_Preserve, Tk_Release, and Tk_EventuallyFree
to Tcl, renamed to Tcl_Preserve, Tcl_Release, and Tcl_EventuallyFree. (JO)

12/18/95 (new feature) Added new "package" command and associated
procedures Tcl_PkgRequire and Tcl_PkgProvide.   Also wrote
pkg_mkIndex library procedure to create index files from binaries
and scripts. (JO)

12/20/95 (new feature) Added Tcl_WaitForFile procedure. (JO)

12/21/95 (new features) Made package name argument to "load" optional
(Tcl will now attempt to guess the package name if necessary).  Also
added Tcl_StaticPackage and support in "load" for statically linked
packages.  (JO)

12/22/95 (new feature) Upgraded the foreach command to accept multiple
loop variables and multiple value lists.  This lets you iterate over
multiple lists in parallel, and/or assign multiple loop variables from
one value list during each iteration. The only potential compatibility
problem is with scripts that used loop variables with a name that could be
construed to be a list of variable names (i.e. contained spaces).  (BW)

1/5/96 (new feature) Changed tclsh so it builds as a console mode
application under Windows.  Now tclsh can be used from the command
line with pipes or interactively.  Note that this only works under
Windows 95 or NT. (SS)

1/17/96 (new feature) Modified Makefile and configure script to allow
Tcl to be compiled as a shared library:  use the --enable-shared option
when configuing.  (JO)

1/17/96 (removed obsolete features)  Removed the procedures Tcl_EnterFile
and Tcl_GetOpenFile:  these no longer make sense with the new I/O system. (JL)
*** POTENTIAL INCOMPATIBILITY ***

1/19/96 (bug fixes) Prevented formation of circular aliases, through the
Tcl 'interp alias' command and through the 'rename' command, as well as
through the C API Tcl_CreateAlias. (JL)

1/19/96 (bug fixes) Fixed several bugs in direct deletion of interpreters
with Tcl_DeleteInterp when the interpreter is a slave; fixes based on a
patch received from Viktor Dukhovni of ESM. (JL)

1/19/96 (new feature) Implemented on-close handlers for channels; added
the C APIs Tcl_CreateCloseHandler and Tcl_DeleteCloseHandler. (JL)

1/19/96 (new feature) Implemented portable error reporting mechanism; added
the C APIs Tcl_SetErrno and Tcl_GetErrno. (JL)

1/24/96 (bug fix) Unknown command processing properly invokes external
commands under Windows NT and Windows '95 now. (SS)

1/23/96 (bug fix) Eliminated extremely long startup times under Windows '95.
The problem was a result of the option database initialization code that
concatenated $HOME with /.Xdefaults, resulting in a // in the middle of the
file name.  Under Windows '95, this is incorrectly interpreted as a UNC
path.  They delays came from the network timeouts needed to determine that
the file name was invalid.  Tcl_TranslateFileName now suppresses duplicate
slashes that aren't at the beginning of the file name. (SS)
				     
1/25/96 (bug fix) Changed exec and open to create children so they are
attached to the application's console if it exists. (SS)

1/31/96 (bug fix) Fixed command line parsing to handle embedded
spaces under Windows. (SS)

----------------- Released 7.5b1, 2/1/96 -----------------------

2/7/96 (bug fix) Fixed off by one error in argument parsing code under
Windows. (SS)

2/7/96 (bug fix) Fixed bugs in VC++ makefile that improperly
initialized the tcl75.dll.  Fixed bugs in Borland makefile that caused
build failures under Windows NT. (SS)

2/9/96 (bug fix) Fixed deadlock problem in AUTO end of line translation
mode which would cause a socket server with several concurrent clients
writing in CRLF mode to hang. (JL)

2/9/96 (API change) Replaced -linemode option to fconfigure with a
new -buffering option, added "none" setting to enable immediate write. (JL)
*** INCOMPATIBILITY with b1 ***

2/9/96 (new feature) Added C API Tcl_InputBuffered which returns the count
of bytes currently buffered in the input buffer of a channel, and o for
output only channels. (JL)

2/9/96 (new feature) Implemented asynchronous connect for sockets. (JL)

2/9/96 (new feature) Added C API Tcl_SetDefaultTranslation to set (per
channel) the default end of line translation mode. This is the mode that
will be installed if an output operation is done on the channel while it is
still in AUTO mode. (JL)

2/9/96 (bug fix) Changed Tcl_OpenCommandChannel interface to properly
handle all of the combinations of stdio inheritance in background
pipelines.  See the Tcl_OpenFileChannel(3) man page for more
info.  This change fixes the bug where exec of a background pipeline
was not getting passed the stdio handles properly. (SS)

2/9/96 (bug fix) Removed the new Tcl_CreatePipeline interface, and
restored the old version for Unix platforms only.  All new code should
use Tcl_CreateCommandChannel instead. (SS)

2/9/96 (bug fix) Changed Makefile.in to use -L and -ltcl7.5 for Tcl
library so that shared libraries are more likely to be found correctly
on more platforms. (JO)

2/13/96 (new feature) Added C API Tcl_SetNotifierData and
Tcl_GetNotifierData to allow notifier and channel driver writers to
associate data with a Tcl_File.  The result of this change is that
Tcl_GetFileInfo now always returns an OS file handle, and Tcl_GetFile
can be used to construct a Tcl_File for an externally constructed OS
handle. (SS)

2/13/96 (bug fix) Changed Windows socket implementation so it doesn't
set SO_REUSEADDR on server sockets.  Now attempts to create a server
socket on a port that is already in use will be properly identified
and an error will be generated. (SS)

2/13/96 (bug fix) Fixed problems with DLL initialization under Visual
C++ that left the C run time library uninitialized. (SS)

2/13/96 (bug fix) Fixed Windows socket initialization so it loads
winsock the first time it is used, rather than at the time tcl75.dll
is loaded.  This should fix the bug where the modem immediately starts
trying to connect to a service provider when wish or tclsh are
started. (SS)

2/13/96 (new feature) Added C APIs Tcl_MakeFileChannel and
Tcl_MakeTcpClientChannel to wrap up existing fds and sockets into
channels. Provided implementations on Unix and Windows. (JL)

2/13/96 (bug fix) Fixed bug with seek leaving EOF and BLOCKING set. (JL)

2/14/96 (bug fix) Fixed reentrancy problem in fileevent handling
and made it more robust in the face of errors. (JL)

2/14/96 (feature change) Made generic IO level emulate blocking mode if the
channel driver is unable to provide it, e.g. if the low level device is
always nonblocking. Thus, now blocking behavior is an advisory setting for
channel drivers and can be ignored safely if the channel driver is unable
to provide it. (JL)

2/15/96 (new feature) Added "binary" end of line translation mode, which is
a synonym of "lf" mode. (JL)

2/15/96 (bug fix) Fixed reentrancy problem in fileevent handling vs
deletion of channel event handlers. (JL)

2/15/96 (bug fix) Fixed bug in event handling which would cause a
nonblocking channel to not see further readable events after the first
readable event that had insufficient input. (JL)

2/17/96 (bug fix) "info complete" didn't properly handle comments
in nested commands. (JO)

2/21/96 (bug fix) "exec" under Windows NT/95 did not properly handle
very long command lines (>200 chars). (SS)

2/21/96 (bug fix) Sockets could get into an infinite loop if a read
event arrived after all of the available data had been read. (SS)

2/22/96 (bug fix) Added cast of st_size elements to (long) before
sprintf-ing in "file size" command.  This is needed to handle systems
like NetBSD with 64-bit file offsets.  (JO)

----------------- Released 7.5b2, 2/23/96 -----------------------

2/23/96 (bug fix) TCL_VARARGS macro in tcl.h wasn't defined properly
when compiling with C++.  (JO)

2/24/96 (bug fix) Removed dependencies on Makefile in the UNIX Makefile:
this caused problems on some platforms (like Linux?). (JO)

2/24/96 (bug fix) Fixed configuration bug that made Tcl not compile
correctly on Linux machines with neither -ldl or -ldld. (JO)

2/24/96 (new feature) Added a block of comments and definitions to
Makefile.in to make it easier to have Tcl's TclSetEnv etc. replace
the library procedures setenv etc, so that calls to setenv etc. in
the application automatically update the Tcl "env" variable. (JO)

2/27/96 (feature change) Added optional Tcl_Interp * argument (may be NULL)
to C API Tcl_Close and simplified closing of command channels. (JL)
*** INCOMPATIBILITY with Tcl 7.5b2, but not with Tcl 7.4 ***

2/27/96 (feature change) Added optional Tcl_Interp * argument (may be NULL)
to C type definition Tcl_DriverCloseProc; modified all channel drivers to
implement close procedures that accept the additional argument. (JL)
*** INCOMPATIBILITY with Tcl 7.5b2, but not with Tcl 7.4 ***

2/28/96 (bug fix) Fixed memory leak that could occur if an upvar
referred to an element of an array in the same stack frame as the
upvar. (JO)

2/29/96 (feature change) Modified both Tcl_DoOneEvent and Tcl_WaitForEvent
so that they return immediately in cases where they would otherwise
block forever (e.g. if there are no event handlers of any sort). (JO)

2/29/96 (new feature) Added C APIs Tcl_GetChannelBufferSize and
Tcl_SetChannelBufferSize to set and retrieve the size, in bytes, for
buffers allocated to store input or output in a channel. (JL)

2/29/96 (new feature) Added option -buffersize to Tcl fconfigure command
to allow Tcl scripts to query and set the size of channel buffers. (JL)

2/29/96 (feature removed) Removed channel driver function to specify
the buffer size to use when allocating a buffer. Removed the C typedef
for Tcl_DriverBufferSizeProc. Channels are now created with a default
buffer size of 4K. (JL)
*** INCOMPATIBILITY with Tcl 7.5b2, but not with Tcl 7.4 ***

2/29/96 (feature change) The channel driver function for setting blocking
mode on the device may now be NULL. If the generic code detects that the
function is NULL, operations that set the blocking mode on the channel
simply succeed. (JL)

3/2/96 (bug fix) Fixed core dump that could occur if a syntax error
(such as missing close paren) occurred in an array reference with a
very long array name. (JO)

3/4/96 (bug fix) Removed code in the "auto_load" procedure that deletes
all existing auto-load information whenever the "auto_path" variable
is changed.  Instead, new information adds to what was already there.
Otherwise, changing the "auto_path" variable causes all package-
related information to be lost.  If you really want to get rid of
existing auto-load information, use auto_reset before setting auto_path. (JO)

3/5/96 (new feature) Added version suffix to shared library names so that
Tcl will compile under NetBSD and FreeBSD (I hope).  (JO)

3/6/96 (bug fix) Cleaned up error messages in new I/O system to correspond
more closely to old I/O system. (JO)

3/6/96 (new feature) Added -myaddr and -myport options to the socket
command, removed -tcp and -- options.  This lets clients and servers
choose a particular interface.  Also changed the default server address
from the hostname to INADDR_ANY.  The server accept callback now gets
passed the client's port as well as IP address.  The C interfaces for
Tcl_OpenTcpClient and Tcl_OpenTcpServer have changed to support the
above changes. (BW)
*** POTENTIAL INCOMPATIBILITY with Tcl 7.5b2, but not with Tcl 7.4 ***

3/6/96 (changed feature) The library function auto_mkindex will now
default to using the pattern "*.tcl" if no pattern is given. (RJ)

3/6/96 (bug fix) The socket channel code for the Macintosh has been
rewritten to use native MacTcp.  (RJ)

3/7/96 (new feature) Added Tcl_SetStdChannel and Tcl_GetStdChannel
interfaces to allow applications to explicitly set and get the global
standard channels. (SS)

3/7/96 (bug fix) Tcl did close not the file descriptors associated
with "stdout", etc. when the corresponding channels were closed.  (SS)

3/7/96 (bug fix) Reworked shared library and dynamic loading stuff to
try to get it working under AIX.  Added new @SHLIB_LD_LIBS@ autoconf
symbol as part of this.  AIX probably doesn't work yet, but it should
be a lot closer. (JO)

3/7/96 (feature change) Added Tcl_ChannelProc typedef and changed the
signature of Tcl_CreateChannelHandler and Tcl_DeleteChannelHandler to take
Tcl_ChannelProc arguments instead of Tcl_FileProc arguments. This change
should not affect any code outside Tcl because the signatures of
Tcl_ChannelProc and Tcl_FileProc are compatible. (JL)

3/7/96 (API change) Modified signature of Tcl_GetChannelOption to return
an int instead of char *, and to take a Tcl_DString * argument. Modified
the implementation so that the option name can be NULL, to mean that the
call should retrieve a list of alternating option names and values. (JL)
*** INCOMPATIBILITY with Tcl 7.5b2, but not with Tcl 7.4 ***

3/7/96 (API change) Added Tcl_DriverSetOptionProc, Tcl_DriverGetOptionProc
typedefs, added two slots setOptionProc and getOptionProc to the channel
type structure. These may be NULL to indicate that the channel type does
not support any options. (JL)
*** INCOMPATIBILITY with Tcl 7.5b2, but not with Tcl 7.4 ***

3/7/96 (feature change) stdin, stdout and stderr can now be put into
nonblocking mode. (JL)

3/8/96 (feature change) Eliminated dependence on the registry for
finding the Tcl library files. (SS)

----------------- Released 7.5b3, 3/8/96 -----------------------

3/12/96 (feature improvement) Modified startup script to look in several
different places for the Tcl library directory.  This should allow Tcl
to find the libraries under all but the weirdest conditions, even without
the TCL_LIBRARY environment variable being set. (JO)

3/13/96 (bug fix) Eliminated use of the "linger" option from the Windows
socket implementation. (JL)

3/13/96 (new feature) Added -peername and -sockname options for fconfigure
for socket channels. Code contributed by John Haxby of HP. (JL)

3/13/96 (bug fix) Fixed panic and core dump that would occur if the accept
callback script on a server socket encountered an error. (JL)

3/13/96 (feature change) Added -async option to the Tcl socket command.
If the command is creating a client socket and the flag is present, the
client is connected asynchronously. If the option is absent (the default),
the client socket is connected synchronously, and the command returns only
when the connection has been completed or failed. This change was suggested
by Mark Diekhans. (JL)

3/13/96 (feature change) Modified the signature of Tcl_OpenTcpClient to
take an additional int argument, async. If nonzero, the client is connected
to the server asynchronously. If the value is zero, the connection is made
synchronously, and the call to Tcl_OpenTcpClient returns only when the
connection fails or succeeds. This change was suggested by Mark Diekhans. (JL)
*** INCOMPATIBILITY with Tcl 7.5b3, but not with Tcl 7.4 ***

3/14/96 (bug fix) "tclsh bogus_file_name" didn't print an error message. (JO)

3/14/96 (bug fix) Added new procedures to tclCkalloc.c so that libraries
and applications can be compiled with TCL_MEM_DEBUG even if Tcl isn't
(however, the converse is still not true).  Patches provided by Jan
Nijtmans. (JO)

3/15/96 (bug fix) Marked standard IO handles of a process as close-on-exec
to fix bug in Ultrix where exec was not sharing standard IO handles with
subprocesses. Fix suggested by Mark Diekhans. (JL)

3/15/96 (bug fix) Fixed asynchronous close mechanism so that it closes the
channel instead of leaking system resources. The manifestation was that Tcl
would eventually run out of file descriptors if it was handling a large
number of nonblocking sockets or pipes with high congestion. (JL)

3/15/96 (bug fix) Fixed tests so that they no longer leak file descriptors.
The manifestation was that Tcl would eventually run out of file descriptors
if the tests were rerun many times (> a hundred times on Solaris). (JL)

3/15/96 (bug fix) Fixed channel creation code so that it never creates
unnamed channels. This would cause a panic and core dump when the channel
was closed. (JL)

3/16/96 (bug fixes) Made lots of changes in configuration stuff to get
Tcl working under AIX (finally).  Tcl should now support the "load"
command under AIX and should work either with or without shared
libraries for Tcl and Tk. (JO)

3/21/96 (configuration improvement) Changed configure script so it
doesn't use version numbers (as in -ltcl7.5 and libtcl7.5.so) under
SunOS 4.1, where they don't work anyway.  (JO)

3/22/96 (new feature) Added C API Tcl_InterpDeleted that allows extension
writers to discover when an interpreter is being deleted. (JL)

3/22/96 (bug fix) The standard IO channels are now added to each
trusted interpreter as soon as the interpreter is created. This ensures
against the bug where a child would do IO before the master had done any,
and then the child is destroyed - the standard IO channels would be then
closed and the master would be unable to do any IO. (JL)

3/22/96 (bug fix) Made Tcl more robust against interpreter deletion, by
using Tcl_Preserve, Tcl_Release and Tcl_EventuallyFree to split the process
of interpreter deletion into two distinct phases. Also went through all of
Tcl and added calls to Tcl_Preserve and Tcl_Delete where needed. (JL)

3/22/96 (bug fix) Fixed several places where C code was reading and writing
into freed memory, especially during interpreter deletion. (JL)

3/22/96 (bug fix) Fixed very deep bug in Tcl_Release that caused memory to
be freed twice if the release callback did Tcl_Preserve and Tcl_Release on
the same memory as the chunk currently being freed. (JL)

3/22/96 (bug fix) Removed several memory leaks that would cause memory
buildup on half-K chunks in the generic IO level. (JL)

3/22/96 (bug fix) Fixed several core dumps which occurred when new
AssocData was being created during the cleanups in interpreter deletion.
The solution implemented now is to loop repeatedly over the AssocData until
none is left to clean up. (JL)

3/22/96 (bug fix) Fixed a bug in event handling which caused an infinite
loop if there were no files being watched and no timer. Fix suggested by
Jan Nijtmans. (JL)

3/22/96 (bug fix) Fixed Tcl_CreateCommand, Tcl_DeleteCommand to be more
robust if the interpreter is being deleted. Also fixed several order
dependency bugs in Tcl_DeleteCommand which kicked in when an interpreter
was being deleted. (JL)

3/26/96 (bug fix) Upon a "short read", the generic code no longer calls
the driver for more input. Doing this caused blocking on some platforms
even on nonblocking channels. Bug and fix courtesy Mark Roseman. (JL)

3/26/96 (new feature) Added 'package Tcltest' which is present only in
test versions of Tcl; this allows the testing commands to be loaded into
new interpreters besides the main one. (JL)

3/26/96 (restored feature) Recreated the Tcl_GetOpenFile C API. You can
now get a FILE * from a registered channel; Unix only. (JL)

3/27/96 (bug fix) The regular expression code did not support more
than 9 subexpressions.  It now supports up to 20. (SS)

4/1/96 (bug fixes) The CHANNEL_BLOCKED bit was being left on on a short
read, so that fileevents wouldn't fire correctly. Bug reported by Mark
Roseman.(JL, RJ)

4/1/96 (bug fix) Moved Tcl_Release to match Tcl_Preserve exactly, in
tclInterp.c; previously interpreters were being freed only conditionally
and sometimes not at all. (JL)

4/1/96 (bug fix) Fixed error reporting in slave interpreters when the
error message was being generated directly by C code. Fix suggested by
Viktor Dukhovni of ESM. (JL)

4/2/96 (bug fixes) Fixed a series of bugs in Windows sockets that caused
events to variously get lost, to get sent multiple times, or to be ignored
by the driver. The manifestation was blocking if the channel is blocking,
and either getting EAGAIN or infinite loops if the channel is nonblocking.
This series of bugs was found by Ian Wallis of Cisco. Now all tests (also
those that were previously commented out) in socket.test pass.  (JL, SS)

4/2/96 (feature change/bug fix) Eliminated network name support in
favor of better native name support.  Added "file split", "file join",
and "file pathtype" commands.  See the "file" man page for more
details. (SS)
*** INCOMPATIBILITY with Tcl 7.5b3, but not with Tcl 7.4 ***

4/2/96 (bug fix) Changed implementation of auto_mkindex so tclIndex
files will properly handle path names in a cross platform context. (SS)

4/5/96 (bug fix) Fixed Tcl_ReadCmd to use the channel buffer size as the
chunk size it reads, instead of a fixed 4K size. Thus, on large reads, the
user can set the channel buffer size to a large size and the read will
occur orders of magnitude faster. For example, on a 2MB file, reading in 4K
chunks took 34 seconds, while reading in 1MB chunks took 1.5 seconds (on a
SS-20). Problem identified and fix suggested by John Haxby of HP. (JL)

4/5/96 (bug fix) Fixed socket creation code to invoke gethostbyname only if
inet_addr failed (very unlikely). Before this change the order was reversed
and this made things much slower than they needed to be (gethostbyname
generally requires an RPC, which is slow). Problem identified and fix
suggested by John Loverso of OSF. (JL)

4/9/96 (feature change) Modified "auto" translation mode so that it
recognizes any of "\n", "\r" and "\r\n" in input as end of line, so
that a file can have mixed end-of-line sequences. It now outputs
the platform specific end of line sequence on each platform for files and
pipes, and for sockets it produces crlf in output on all platforms. (JL)
*** INCOMPATIBILITY with Tcl 7.5b3, but not with Tcl 7.4 ***

4/11/96 (new feature) Added -eofchar option to Tcl_SetChannelOption to allow
setting of an end of file character for input and output. If an input eof
char is set, it is recognized as EOF and further input from the channel is
not presented to the caller. If an output eof char is set, on output, that
byte is appended to the channel when it is closed. On Unix and Macintosh,
all channels start with no eof char set for input or output. On Windows,
files and pipes start with input and output eof chars set to Crlt-Z (ascii
26), and sockets start with no input or output eof char. (JL)
*** INCOMPATIBILITY with Tcl 7.5b3, but not with Tcl 7.4 ***

4/17/96 (bug fix) Fixed series of bugs with handling of crlf sequence split
across buffer boundaries in input, in AUTO mode. (JL, BW)

4/17/96 (test suite improvement) Fixed test suite so that tests that
depend on the availability of Unix commands such as echo, cat and others
are not run if these commands are not present. (JL)

4/17/96 (test suite improvement) The socket test now automatically starts,
on platformst that support exec, a separate process for remote testsing. (JL)

----------------- Released 7.5, 4/21/96 -----------------------

5/1/96 (bug fix) "file tail ~" did not correctly return the tail
portion of the user's home directory. (SS)

5/1/96 (bug fix) Fixed bug in TclGetEnv where it didn't lookup environment
variables correctly:  could confuse "H" and "HOME", for example.  (JO)

5/1/96 (bug fix) Changed to install tclConfig.sh under "make install-binaries",
not "make install-libraries".  (JO)

5/2/96 (bug fix) Changed pkg_mkIndex not to attempt to "load" a file unless
it has the standard shared library extension.  On SunOS, attempts to load
Tcl scripts cause the whole application to be aborted (there's no way to
get the error back into Tcl).  (JO)

5/7/96 (bug fix) Moved initScript in tclUnixInit.c to writable memory to
avoid potential core dumps. (JO)

5/7/96 (bug fix) Auto_reset procedure was removing procedure from init.tcl,
such as pkg_mkIndex.  (JO)

5/7/96 (bug fix) Fixed cast on socket address resolution code that
would cause a failure to connect on Dec Alphas. (JL)

5/7/96 (bug fix) Added "time", "subst" and "fileevent" commands to set of
commands available in a safe interpreter. (JL)

5/13/96 (bug fix) Preventing OS level handles for stdin, stdout and stderr
from being implicitly closed when the last reference to the standard
channel containing that handle is discarded when an interpreter is deleted.
Explicitly closing standard channels by using "close" still works. (JL)

5/21/96 (bug fix) Do not create channels for stdin, stdout and stderr on
Unix if the devices are closed. This prevents a duplicate channel name
panic later on when the fd is used to open a channel and the channel is
registered in an interpreter. (JL)

5/23/96 (bug fix) Fixed bug that prevented the use of standard channels in
interpreters created after the last interpreter was destroyed. In the sequence

	interp = Tcl_CreateInterp();
	Tcl_DeleteInterp(interp);
	interp = Tcl_CreateInterp();

channels for stdio would not be available in the second interpreter. (JL)

5/23/96 (bug fix) Fixed bug that allowed Tcl_MakeFileChannel to create new
channels with Tcl_Files in them that are already used by another channel.
This would cause core dumps when the Tcl_Files were being freed twice. (JL)

5/23/96 (bug fix) Fixed a logical timing bug that caused a standard channel
to be removed from the standard channel table too early when the channel
was being closed. If the channel was being flushed asynchronously, it could
get recreated before being actually destroyed, and the recreated channel
would contain the same Tcl_File as the one being closed, leading to
dangling pointers and core dumps. (JL)

5/27/96 (bug fix) Fixed a bug in Tcl_GetChannelOption which caused it to
always return a list of one element, a list of the settings, for
-translation and -eofchar options. Now correctly returns the value
described by the documentation (Mark Diekhans found this, thanks!). (JL)

5/30/96 (bug fix) Fixed a couple of syntax errors in io.test. (JL)

5/30/96 (bug fix) If a fileevent scripts gets an error, delete it before
causing a background error. This is to allow the error handler to reinstall
the fileevent and to prevent infinite loops if the event loop is reentered
in the error handler. (JL)

5/31/96 (bug fix) Channels now will get properly flushed on exit. (JL)

6/5/96 (bug fix) Changed Tcl_Ckalloc, Tcl_Ckfree, and Tcl_Ckrealloc to
Tcl_Alloc, Tcl_Free, and Tcl_Realloc.  Added documentation for these
routines now that they are officially supported.  Extension writers
should use these routines instead of free() and malloc(). (SS)

6/10/96 (bug fix) Changes the Tcl close command so that it no longer
waits on nonblocking pipes for the piped processes to exit; instead it
reaps them in the background. (JL)

6/11/96 (bug fix) Increased the length of the listen queue for server
sockets on Unix from 5 to 100. Some OSes will disregard this and reset it
to 5, but we should try to get as long a queue as we can, for performance
reasons. (JL)

6/11/96 (bug fix) Fixed windows sockets bug that caused a cascade of events
if the fileevent script read less than was available. Now reading less than
is available does not cause a flood of Tcl events. (JL, SS)

6/11/96 (bug fix) Fixed bug in background flushing on closed channels that
would prevent the last buffer from getting flushed. (JL)

6/13/96 (bug fix) Fixed bug in Windows sockets that caused a core dump if
a DLL linked with tcl.dll and referred to e.g. ntohs() without opening a
Tcl socket. The problem was that the indirection table was not being
initialized. (JL)

6/13/96 (bug fix) Fixed OS level resource leak that would occur when a
Tcl channel was still registered in some interpreter when the process
exits. Previously the channel was not being closed and the OS level handles
were not being released; the output was being flushed but the device was
not being closed. Now the device is properly closed. This was only a
problem on Win3.1 and MacOS. (JL, SS)

6/28/96 (bug fix) Fixed bug where transient errors were leaving an error
code around, so that it would erroneously get reported later. This bug was
exercised intermittently by closing a channel to a file on a very loaded
NFS server, or to a socket whose other end blocked. (JL, BW)

7/3/96 (bug fix) Fileevents declared in an interpreter are now deleted
when the channel is closed in that interpreter. Before this fix, the
fileevent would hang around until the channel is completely closed, and
would cause errors if events happened before the channel was closed. This
could happen in two cases: first if the channel is shared between several
interpreters, and second if an async flush is in progress that prevents the
channel from being closed until the flush finishes. (JL)

7/10/96 (bug fix) Fixed bugs in both "lrange" and "lreplace" commands
where too much white space was being removed. For example, the command
		lreplace {\}\     hello} end end
was returning "\}\", losing the significant space in the first list
element and corrupting the list. (JO)

7/20/96 (bug fix) The procedure pkg_mkIndex didn't work properly for
extensions that depend on Tk, because it didn't load Tk into the child
interpreter before loading the extension.  Now it loads Tk if Tk is
present in the parent. (JO)

7/23/96 (bug fix) Added compat version of strftime to fix crashes
resulting from bad implementations under Windows. (SS)

7/23/96 (bug fix) Standard implementations of gmtime() and localtime()
under Windows did not handle dates before 1970, so they were replaced
with a revised implementation. (SS)

7/23/96 (bug fix) Tcl would crash on exit under Borland 5.0 because
the global environ pointer was left pointing to freed memory. (SS)

7/29/96 (bug fix) Fixed memory leak in Tcl_LoadCmd that could occur if
a package's AppInit procedure called Tcl_StaticPackage to register
static packages. (JO)

8/1/96 (bug fix) Fixed a series of bugs in Windows sockets so that async
writebehind in the presence of read event handlers now works, and so that
async writebehind also works on sockets for which a read event handler was
declared and whose channels were then closed before the async write
finished. The bug was reported by John Loverso and Steven Wahl,
independently, test case supplied by John Loverso. (JL)

----------------- Released patch 7.5p1, 8/2/96 -----------------------

5/8/96 (API changes) Revised C APIs for channel drivers:
    - Removed all Tcl_Files from channel driver interface; you can now have
      channels that are not based on Tcl_Files.
    - Added channelReadyProc and watchChannelProc procedures to interface;
      these are used to implement event notification for channels.
    - Added getFileProc to channel driver, to allow the generic IO code
      to retrieve a Tcl_File from a channel (presumably if the channel
      uses Tcl_Files they will be stored inside its instanceData). (JL)
*** INCOMPATIBILITY with Tcl 7.5 ***

5/8/96 (API change) The Tcl_CreateChannel C API was modified to not take
Tcl_File arguments, and instead to take a mask specifying whether the
channel is readable and/or writable. (JL)
*** INCOMPATIBILITY with Tcl 7.5 ***

5/8/96 (new feature) Added Tcl_Ungets C API for putting a sequence of bytes
into a channel's input buffer. This can be used for "push" model channels
where the input is obtained via callbacks instead of by request of the
generic IO code. (JL)

5/8/96 (new feature) Added Tcl_GetChannelMode C API for retrieving whether
a channel is open for reading and writing. (JL)

6/3/96 (bug fix) Made Tcl_SetVar2 robust against the case where the value
of the variable is a NULL pointer instead of "". (JL)

6/17/96 (bug fix) Fixed "reading uninitialized memory" error reported by
Purify, in Tcl_Preserve/Tcl_Release. (JL)

8/9/96 (bug fix) Fixed bug in init.tcl that caused incorrect error message
if the act of autoloading a procedure caused the procedure to be invoked
again. (JO)

8/9/96 (bug fix) Configure script produced bad library names and extensions
under SunOS and a few other platforms if the --disable-load switch was used.
(JO)

8/9/96 (bug fix) Tcl_UpdateLinkedVar generated an error if the variable
being updated was read-only. (JO)

8/14/96 (bug fix) The macintosh now supports synchronous socket
connections.  Other minor bugs were also fixed. (RJ)

8/15/96 (configuration improvement) Changed the file patchlevel.h
to be tclPatch.h.  This avoids conflict with the Tk file and is now
in 8.3 format on the Windows platform. (RJ)

8/20/96 (bug fix) Fixed core dump in interp alias command for interpreters
created with Tcl_CreateInterp (as opposed to with Tcl_CreateSlave). (JL)

8/20/96 (bug fix) No longer masking ECONNRESET on Windows sockets so
that the higher level of the IO mechanism sees the error instead of
entering an infinite loop. (JL)

8/20/96 (bug fix) Destroying the last interpreter no longer closes the
standard channels. (JL)

8/20/96 (bug fix) Closing one of the stdin, stdout or stderr channels and
then opening a new channel now correctly assigns the new channel as the
standard channel that was closed. (JL)

8/20/96 (bug fix) Added code to unix/tclUnixChan.c for using ioctl with
FIONBIO instead of fcntl with O_NONBLOCK, for those versions of Unix where
either O_NONBLOCK is not supported or implemented incorrectly. (JL)

8/21/96 (bug fix) Fixed "file extension" so it correctly returns the
extension on files like "foo..c" as "..c" instead of ".c". (SS)

8/22/96 (bug fix) If environ[] contains static strings, Tcl would core
dump in TclSetupEnv because it was trying to write NULLs into the actual
data in environ[]. Now we instead copy as appropriate. (JL)

8/22/96 (added impl) Added missing implementation of Tcl_MakeTcpClientChannel
for Windows platform. Code contributed by Mark Diekhans. (JL)

8/22/96 (new feature) Added a new memory allocator for the Macintosh
version of Tcl.  It's quite a bit faster than MetroWerk's version. (RJ)

8/26/96 (documentation update) Removed old change bars (for all changes
in Tcl 7.5 and earlier releases) from manual entries. (JO)

8/27/96 (enhancement) The exec and open commands behave better and work in 
more situations under Windows NT and Windows 95.  Documentation describes 
what is still lacking. (CS)

8/27/96 (enhancement) The Windows makefiles will now compile even if the
compiler is not in the path and/or the compiler's environment variables
have not been set up. (CS) 

8/27/96 (configuration improvement) The Windows resource files are 
automatically updated when the version/patch level changes.  The header file
now has a comment that reminds the user which other files must be manually
updated when the version/patch level changes. (CS)

8/28/96 (new feature) Added file manipulation features (copy, rename, delete,
mkdir) that are supported on all platforms. They are implemented as 
subcommands to the "file" command. See the documentation for the "file"
command for more information. (JH)

----------------- Released 7.6b1, 8/30/96 -----------------------

9/3/96 (bug fix) Simplified code so that standard channels are created
lazily, they are added to an interpreter lazily, and they are never added
to a safe interpreter. (JL)

9/3/96 (bug fix) Closing a channel after closing a standard channel, e.g.
stdout, would cause the implicit recreation of that standard channel. (JL)

9/3/96 (new feature) Now calling Tcl_RegisterChannel with a NULL
interpreter increments the refcount so that code outside any interpreter
can use channels that are also registered in interpreters, without worrying
that the channel may turn into a dangling pointer at any time. Calling
Tcl_UnregisterChannel with a NULL interpreter only decrements the recount
so that code outside any interpreter can safely declare it is no longer
interested in a channel. (JL)

9/4/96 (new features) Two changes to dynamic loading:
    - If the file name is empty in the "load" command and there is no
      statically loaded version of the package, a dynamically loaded
      version will be used if there is one.
    - Tcl_StaticPackage ignores redundant calls for the same package. (JO)

9/6/96 (bug fix) Platform specific procedures for manipulating files are
no longer macros and have been prefixed with "Tclp", such as TclpRenameFile.
Unix file code now handles symbolic links and other special files correctly.
The semantics of file copy and file rename has been changed so that if
a target directory exists, the source files will NOT be merged with the
existing files. (JH)

9/6/96 (bug fix) If standard channel is NULL, because Tcl cannot connect
to the standard channel, do not increment the refcount. The channel can
be NULL if there is for example no standard input. (JL)

9/6/96 (portability improvement) Changed parsing of backslash sequences
like \n to translate directly to absolute values like 0xa instead of
letting the compiler do the translation.  This guarantees that the
translation is done the same everywhere. (JO)

9/9/96 (bug fix) If channel is opened and not associated with any
interpreter, but Tcl decides to use it as one of the standard channels, it
became impossible to close the channel with Tcl_Close -- instead you had
to call Tcl_UnregisterChannel. Fixed now so that it's safe to call
Tcl_Close even when Tcl is using the channel as one of the standard ones. (JL)

9/11/96 (feature change) The Tcl library is now placed in the Tcl
shared libraries resource.  You no longer need to place the Tcl files
in your applications explicitly.  (RJ)

9/11/96 (feature change) Extensions no longer automatically have the
resource fork of the extension opened for it.  Instead you need to
use the tclMacLibrary.c file in your extension.  (RJ)
*** POTENTIAL INCOMPATIBILITY ***

9/12/96 (bug fix) The extension loading mechanism on the Macintosh now
looks at the 'cfrg' resource to determine where to load the code
fragment from.  This means FAT fragments should now work. (RJ)

9/18/96 (enhancement) The exec and open commands behave better and work in
more situations under Windows 3.X.  Documentation describes what is still
lacking.  (CS)

9/19/96 (bug fix) Fixed a panic which would occur if you delete a
non-existent alias before any aliases are created. Now instead correctly
returns an error that the alias is not found. (JL)

9/19/96 (bug fix) Slave interpreters could rename aliases and they would
not get deleted when the alias was being redefined. This led to dangling
pointers etc. (JL)

9/19/96 (bug fix) Fixed a panic where a hash table entry was being deleted
twice during alias management operations. (JL)

9/19/96 (bug fix) Fixed bug in event loop that could cause the input focus
in Tk to get confused during menu traversal, among other problems.  The
problem was related to handling of the "marker" when its event was
deleted. (JO)

9/26/96 (bug fix) Windows was losing EOF on a socket if the FD_CLOSE event
happened to precede any left over FD_READ events. Now correctly remembers
seeing FD_CLOSE, so that trailing FD_READ events are not discarded if they
do not contain any data. This allows Tcl to correctly get a zero read and
notice EOF. (JL)

9/26/96 (bug fix) Was not resetting READABLE state properly on sockets
under Windows if the driver discarded an FD_READ event because no data was
present. Now correctly resets the state. (JL)

9/30/96 (bug fix) Made EOF sticky on Windows sockets, so that fileevent
readable will fire repeatedly until the socket is closed. Previously the
fileevent fired only once. This could lead to never-closed connections if
the Tcl script in the fileevent wasn't closing the socket immediately. (JL)

10/2/96 (new feature) Improved the package loader:
    - Added new variable tcl_pkgPath, which holds the default
      directories under which packages are normally installed (each
      package goes in a separate subdirectory of a directory in
      $tcl_pkgPath).  These directories are included in auto_path by
      default.
    - Changed the package auto-loader to look for pkgIndex.tcl files 
      not only in the auto_path directories but also in their immediate
      children.  This should make it easier to install and uninstall
      packages (don't have to change auto_path or merge pkgIndex.tcl
      files). (JO)

10/3/96 (bug fix) Changed tclsh to look for tclshrc.tcl instead of
tclsh.rc on startup under Windows.  This is more consistent with wish and
uses the right extension. (SS)
*** POTENTIAL INCOMPATIBILITY ***

10/8/96 (bug fix) Convertclock does not parse 24-hour times of the
form "hhmm" correctly when hour = 00.  In the parse code, hour must be
>= 100 for minutes to be non-zero.  Thanks to Lint LaCour for this
bug fix. (RJ)

10/11/96 (bug fix) Under Windows, the pid command returned the process
handle instead of the process id. (SS)

----------------- Released 7.6, 10/16/96 -----------------------
