This document helps you (and me) understand the architecture of this script.
Hopefully it will help you get jump-started when you want to make
modifications.


MAJOR MODULES

NewsClipper.pl: the main program. Creates a NewsClipper::Parser to parse the
input file and create the output. Manages configuration before the script
starts.

NewsClipper::Globals: All the global values and functions

NewsClipper::Parser: Encapsulates the parsing of the template file. Parses an
input file, looking for a newsclipper tag.

NewsClipper::TagParser: Encapsulates the parsing of the News Clipper command
to get the individual commands. The commands are then sent to the Interpreter.

NewsClipper::Interpreter: Receives commands from the Parser. It tries to fill
in the default filters and output handlers as specified by the input handler,
if necessary. It then creates a HandlerFactory object, which it uses to create
an instance of the handler needed for each command. It then calls the
handler's Get, Filter, or Output routine as dictated by the type of command.

NewsClipper::HandlerFactory: Encapsulates the process of finding and/or
updating a handler for a given tag. Tries to load a handler for a given tag
first locally, and then via the network (if the user okays it). 

NewsClipper::Handler: The base class for handlers. Has a generic "new", Get,
Filter, Output, and GetUpdateTimes that can be inherited by most handlers.
Also sets up the handler-specific state cache.

NewsClipper::AcquisitionFunctions: An API of useful functions for grabbing data
from the internet. This is used by handler writers. The base function is
GetUrl, which talks to the cache to see if it is possible to reuse recently
acquired HTML files.

NewsClipper::Cache: Encapsulates the task of caching HTML files acquired by
GetUrl.  Implements "CachedDataUsable", which checks the old output file to
see if we can reuse the old data given the current time and update time
criteria specified by the handler. 

NewsClipper::HTMLTools: An API of useful functions for manipulating HTML. Used
by handler writers.

NewsClipper::Types: Contains type information used by Interpretor to check the
validity of News Clipper command sequences. Also provides support for making
new types.
