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"Whip" is tentatively an acronym for Wiki Hosted In POE.
It's not hosted in POE yet. I kind of need it right away for POE's
web site, so I'm cutting corners.
Whip is copyright 2002 by Rocco Caputo. All rights are reserved.
Whip is free software. You may redistribute it and/or modify it under
the same terms as Perl itself.
Whip's author may be contacted at <> until other
support channels are activated.
Whip itself itself is very small. It provides just enough features to
load pages and either execute them as code or parse them as XML-like
Whip knows three kinds of files, which are determined by their
extensions. Two are code, and the third is renderable data.
The code files end in .do and .tag.
The .do files are directly invokable actions. They are most often
used as form handlers and dynamic content generators.
The .tag files are designed to parse and render XML-like descriptions
into the final markup for a client or user-agent. While the current
state of the project focuses on HTML, it is trivial to generate other
types of markup.
Data files end in .page, and they describe renderable pages made up of
tags. Many of the tags in a .page file may invoke code from .tag
=head1 STATE
The contents of a tag at any given time is called its state.
=head1 TAG TYPES
There are two kinds of tags: Whip tags and parameter tags.
Whip tags are in the form <whip.something></whip.something>. They
describe a high-level piece of content, such as those faux windows
that are in vogue or a tabloid layout.
Parameter tags look like <something></something> and describe aspects
of whatever whip tag they occur in. The text that occurs between a
parameter's opening and closing tag goes into the tag's states' _value
Each whip tag invokes a corresponding .tag file to process it. The
.tag file calls render_thing() to parse the tag's description and
render it into a new state. The new state may contain data, rendered
markup, or both.
render_thing() returns the new state to its caller, which in turn
assimilates the information it needs and possibly returns yet another
state to its caller. This may recurse several levels deep depending
on the nature of the page.
We'll look at pane.tag as it currently stands.
The pane.tag file defines how the whip markup between <whip.pane> and
</whip.pane> will be parsed and rendered. Whip generates the package
name for a .tag file by replacing the leading "whip." part with
The first section satisfies a few different programs. Tell emacs that
this is a perl file. Tell CVS to include information about the file.
Declare the package, and set the B&D options.
# -*- perl -*-
# $Id$
package Whip::Tag::pane;
use warnings;
use strict;
Next we define the parameters that this whip tag will understand. As
we covered in L<TAG TYPES>, each parameter tag's value is stored in a
_value attribute of the tag's state. The Whip::Tag::as_value()
function moves the value of _value to a new attribute named after the
tag being processed.
In this example, when <title></title> is finished, the contents of
_value are moved to the "title" attribute.
my %tags =
( title => \&Whip::Tag::as_value,
color => \&Whip::Tag::as_value,
item => \&Whip::Tag::as_value,
Finally we define the function that is run to deal with the tag. This
function does some preliminary setup, then calls render_thing() with
the current tag's $state, the name of the tag being rendered, and the
parameter tags to recognize.
Internally, render_tag() will create new states for each tag it
encounters. Those states will inherit $state, which ultimately
inherits from the parser's own state.
render_tag() uses the tag name to search for an appropriate closing
tag. That's how it knows when to return.
render_tag() returns the parsed tag's state, so that run() can extract
values from it and format them. Here run() fetches two scalars and a
list: color, title, and item respectively.
run() then renders the parsed tag's values into the output markup
(HTML in this case) and stores it in the current state's _thing
attribute. This lets run() build a "thing" which may in turn be used
as an element in some larger thing.
The $state also contains an _output attribute. Storing the rendered
markup to _output would append it to the page's output rather than
allow it to be nested inside something else.
Then we return the augmented state for some other thing to process.
sub run {
my ($pkg, $state) = @_;
my $new_state = main::render_thing($state, "whip.pane", \%tags);
my $color = $new_state->fetch("color", "#666666");
my $title = $new_state->fetch("title", "Untitled");
my @items = $new_state->fetch("item");
( _thing =>
( "<table cellpadding='2' cellspacing='3' border='0' width='100%' " .
"bgcolor='$color'>" .
"<tbody>" .
"<tr>" .
"<td valign='top'><font color='#ffffff'>$title</font><br> " .
"</td>" .
"</tr>" .
"<tr>" .
"<td valign='top' bgcolor='#ffffff'>" .
join("<br>", @items) .
"</td>" .
"</tr>" .
"</tbody>" .
return $state;
# Satisfy C<require>.
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