=head1 NAME

Template::Document - a compiled template document

=head1 SYNOPSIS

    use Template::Document;

    $doc = Template::Document->new({
	BLOCK => sub { # some perl code; return $some_text },
	DEFBLOCKS => {
	    header => sub { # more perl code; return $some_text },
	    footer => sub { # blah blah blah; return $some_text },
	},
	METADATA => {
	    author  => 'Andy Wardley',
	    version => 3.14,
	}
    }) || die $Template::Document::ERROR;

    print $doc->process($context);

=head1 DESCRIPTION

This module defines an object class whose instances represent compiled
template documents.  The Template::Parser module creates a
Template::Document instance to encapsulate a template as it is compiled
into Perl code.

The constructor method, new(), expects a reference to a hash array
containing the BLOCK, DEFBLOCKS and METADATA items.  The BLOCK item
should contain a reference to a Perl subroutine or a textual
representation of Perl code, as generated by the Template::Parser
module, which is then evaluated into a subroutine reference using
eval().  The DEFLOCKS item should reference a hash array containing
further named BLOCKs which may be defined in the template.  The keys
represent BLOCK names and the values should be subroutine references
or text strings of Perl code as per the main BLOCK item.  The METADATA
item should reference a hash array of metadata items relevant to the
document.

The process() method can then be called on the instantiated
Template::Document object, passing a reference to a Template::Content
object as the first parameter.  This will install any locally defined
blocks (DEFBLOCKS) in the the contexts() BLOCKS cache (via a call to
visit()) so that they may be subsequently resolved by the context.  The 
main BLOCK subroutine is then executed, passing the context reference
on as a parameter.  The text returned from the template subroutine is
then returned by the process() method, after calling the context leave()
method to permit cleanup and de-registration of named BLOCKS previously
installed.

An AUTOLOAD method provides access to the METADATA items for the document.
The Template::Service module installs a reference to the main 
Template::Document object in the stash as the 'template' variable.
This allows metadata items to be accessed from within templates, 
including PRE_PROCESS templates.

header:
    <html>
    <head>
    <title>[% template.title %]
    </head>
    ...

Template::Document objects are usually created by the Template::Parser
but can be manually instantiated or sub-classed to provide custom
template components.

=head1 METHODS

=head2 new(\%config)

Constructor method which accept a reference to a hash array containing the
structure as shown in this example:

    $doc = Template::Document->new({
	BLOCK => sub { # some perl code; return $some_text },
	DEFBLOCKS => {
	    header => sub { # more perl code; return $some_text },
	    footer => sub { # blah blah blah; return $some_text },
	},
	METADATA => {
	    author  => 'Andy Wardley',
	    version => 3.14,
	}
    }) || die $Template::Document::ERROR;

BLOCK and DEFBLOCKS items may be expressed as references to Perl subroutines
or as text strings containing Perl subroutine definitions, as is generated
by the Template::Parser module.  These are evaluated into subroutine references
using eval().

Returns a new Template::Document object or undef on error.  The error() class
method can be called, or the $ERROR package variable inspected to retrieve
the relevant error message.

=head2 process($context)

Main processing routine for the compiled template document.  A reference to 
a Template::Context object should be passed as the first parameter.  The 
method installs any locally defined blocks via a call to the context 
visit() method, processes it's own template, passing the context reference
by parameter and then calls leave() in the context to allow cleanup.

    print $doc->process($context);

Returns a text string representing the generated output for the template.
Errors are thrown via die().

=head2 block()

Returns a reference to the main BLOCK subroutine.

=head2 blocks()

Returns a reference to the hash array of named DEFBLOCKS subroutines.

=head2 AUTOLOAD

An autoload method returns METADATA items.

    print $doc->author();

=head1 PACKAGE SUB-ROUTINES

=head2 write_perl_file(\%config)

This package subroutine is provided to effect persistance of compiled templates.
If the COMPILE_EXT option (to indicate a file extension for saving compiled
templates) then the Template::Parser module call this subroutine before 
calling the new() constructor.  At this stage, the parser has a representation
of the template as text strings containing Perl code.  We can write that to
a file, enclosed in a small wrapper which will allow us to susequently 
require() the file and have Perl parse and compile it into a Template::Document.
Thus we have persistance of compiled templates.  

=head1 AUTHOR

Andy Wardley E<lt>abw@kfs.orgE<gt>

    http://www.template-toolkit.org/
    http://www.kfs.org/~abw/

=head1 REVISION

$Revision: 1.1 $

=head1 COPYRIGHT

    Copyright (C) 1996-2000 Andy Wardley.  All Rights Reserved.
    Copyright (C) 1998-2000 Canon Research Centre Europe Ltd.

This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.


=head1 SEE ALSO


L<Template|Template>, 
L<Template::Parser|Template::Parser>