1Pod::Constants(3) User Contributed Perl Documentation Pod::Constants(3)
2
6 Pod::Constants - Include constants from POD
7
9 our ($myvar, $VERSION, @myarray, $html, %myhash);
10 use Pod::Constants -trim => 1,
12 'Pod Section Name' => \$myvar,
13 'Version' => sub { eval },
14 'Some list' => \@myarray,
15 html => \$html,
16 'Some hash' => \%myhash;
17 =head2 Pod Section Name
19 This string will be loaded into $myvar
21 =head2 Version
23 # This is an example of using a closure. $_ is set to the
25 # contents of the paragraph. In this example, "eval" is
26 # used to execute this code at run time.
27 $VERSION = 0.19;
28 =head2 Some list
30 Each line from this section of the file
32 will be placed into a separate array element.
33 For example, this is $myarray[2].
34 =head2 Some hash
36 This text will not go into the hash, because
38 it doesn't look like a definition list.
39 key1 => Some value (this will go into the hash)
40 var2 => Some Other value (so will this)
41 wtf = This won't make it in.
42 =head2 %myhash's value after the above:
44 ( key1 => "Some value (this will go into the hash)",
46 var2 => "Some Other value (so will this)" )
47 =begin html <p>This text will be in $html</p>
49 =cut
51
53 This module allows you to specify those constants that should be
54 documented in your POD, and pull them out a run time in a fairly
55 arbitrary fashion.
56 Pod::Constants uses Pod::Parser to do the parsing of the source file.
58 It has to open the source file it is called from, and does so directly
59 either by lookup in %INC or by assuming it is $0 if the caller is
60 "main" (or it can't find %INC{caller()})
61 ARBITARY DECISIONS
63 I have made this code only allow the "Pod Section Name" to match
64 `headN', `item', `for' and `begin' POD sections. If you have a good
65 reason why you think it should match other POD sections, drop me a line
66 and if I'm convinced I'll put it in the standard version.
67 For `for' and `begin' sections, only the first word is counted as being
69 a part of the specifier, as opposed to `headN' and `item', where the
70 entire rest of the line counts.
71
73 import(@args)
74 This function is called when we are "use"'d. It determines the source
75 file by inspecting the value of caller() or $0.
76 The form of @args is HOOK => $where.
78 $where may be a scalar reference, in which case the contents of the POD
80 section called "HOOK" will be loaded into $where.
81 $where may be an array reference, in which case the contents of the
83 array will be the contents of the POD section called "HOOK", split into
84 lines.
85 $where may be a hash reference, in which case any lines with a "=>"
87 symbol present will have everything on the left have side of the =>
88 operator as keys and everything on the right as values. You do not
89 need to quote either, nor have trailing commas at the end of the lines.
90 $where may be a code reference (sub { }), in which case the sub is
92 called when the hook is encountered. $_ is set to the value of the POD
93 paragraph.
94 You may also specify the behaviour of whitespace trimming; by default,
96 no trimming is done except on the HOOK names. Setting "-trim => 1"
97 turns on a package "global" (until the next time import is called) that
98 will trim the $_ sent for processing by the hook processing function
99 (be it a given function, or the built-in array/hash splitters) for
100 leading and trailing whitespace.
101 The name of HOOK is matched against any "=head1", "=head2", "=item",
103 "=for", "=begin" value. If you specify the special hooknames "*item",
104 "*head1", etc, then you will get a function that is run for every
105 Note that the supplied functions for array and hash splitting are
107 exactly equivalent to fairly simple Perl blocks:
108 Array:
110 HOOK => sub { @array = split /\n/, $_ }
112 Hash:
114 HOOK => sub {
116 %hash =
117 (map { map { s/^\s+|\s+$//g; $_ } split /=>/, $_ }
118 (grep m/^
119 ( (?:[^=]|=[^>])+ ) # scan up to "=>"
120 =>
121 ( (?:[^=]|=[^>])+ =? )# don't allow more "=>"'s
122 $/x, split /\n/, $_));
123 }
124 Well, they're simple if you can grok map, a regular expression like
126 that and a functional programming style. If you can't I'm sure it is
127 probably voodoo to you.
128 Here's the procedural equivalent:
130 HOOK => sub {
132 for my $line (split /\n/, $_) {
133 my ($key, $value, $junk) = split /=>/, $line;
134 next if $junk;
135 $key =~ s/^\s+|\s+$//g
136 $value =~ s/^\s+|\s+$//g
137 $hash{$key} = $value;
138 }
139 },
140 import_from_file($filename, @args)
142 Very similar to straight "import", but you specify the source filename
143 explicitly.
144 add_hook(NAME => value)
146 This function adds another hook, it is useful for dynamic updating of
147 parsing through the document.
148 For an example, please see t/01-constants.t in the source distribution.
150 More detailed examples will be added in a later release.
151 delete_hook(@list)
153 Deletes the named hooks. Companion function to add_hook
154 CLOSURES AS DESTINATIONS
156 If the given value is a ref CODE, then that function is called, with $_
157 set to the value of the paragraph. This can be very useful for
158 applying your own custom mutations to the POD to change it from human
159 readable text into something your program can use.
160 After I added this function, I just kept on thinking of cool uses for
162 it. The nice, succinct code you can make with it is one of
163 Pod::Constant's strongest features.
164 Below are some examples.
166
168 Module Makefile.PL maintenance
169 Tired of keeping those module Makefile.PL's up to date? Note: This
170 method seems to break dh-make-perl.
171 Example Makefile.PL
173 eval "use Pod::Constants";
174 ($Pod::Constants::VERSION >= 0.11)
175 or die <<EOF
176 ####
177 #### ERROR: This module requires Pod::Constants 0.11 or
178 #### higher to be installed.
179 ####
180 EOF
181 my ($VERSION, $NAME, $PREREQ_PM, $ABSTRACT, $AUTHOR);
183 Pod::Constants::import_from_file
184 (
185 'MyTestModule.pm',
186 'MODULE RELEASE' => sub { ($VERSION) = m/(\d+\.\d+)/ },
187 'DEPENDENCIES' => ($PREREQ_PM = { }),
188 -trim => 1,
189 'NAME' => sub { $ABSTRACT=$_; ($NAME) = m/(\S+)/ },
190 'AUTHOR' => \$AUTHOR,
191 );
192 WriteMakefile
194 (
195 'NAME' => $NAME,
196 'PREREQ_PM' => $PREREQ_PM,
197 'VERSION' => $VERSION,
198 ($] >= 5.005 ? ## Add these new keywords supported since 5.005
199 (ABSTRACT => $ABSTRACT,
200 AUTHOR => $AUTHOR) : ()),
201 );
202 Corresponding Module
204 =head1 NAME
205 MyTestModule - Demonstrate Pod::Constant's Makefile.PL usefulness
207 =head2 MODULE RELEASE
209 This is release 1.05 of this module.
211 =head2 DEPENDENCIES
213 The following modules are required to make this module:
215 Some::Module => 0.02
217 =head2 AUTHOR
219 Ima Twat <ima@twat.name>
221 =cut
223 our $VERSION;
225 use Pod::Constants -trim => 1,
226 'MODULE RELEASE' => sub { ($VERSION) = m/(\d+\.\d+) or die };
227
229 Sam Vilain, <samv@cpan.org>
230 Maintained by Marius Gavrilescu, <marius@ieval.ro> since July 2015
232
234 Copyright (C) 2001, 2002, 2007 Sam Vilain. All Rights Reserved.
235 Copyright (C) 2015-2016 by Marius Gavrilescu <marius@ieval.ro>.
237 This module is free software. It may be used, redistributed and/or
239 modified under the terms of the Perl Artistic License, version 2.
240 See the LICENSE file in the root of this distribution for a copy of the
242 Perl Artistic License, version 2.
243
245 I keep thinking it would be nice to be able to import an =item list
246 into an array or something, eg for a program argument list. But I'm
247 not too sure how it would be all that useful in practice; you'd end up
248 putting the function names for callbacks in the pod or something
249 (perhaps not all that bad).
250 Would this be useful?
252 Pod::Constants::import(Foo::SECTION => \$myvar);
254 Debug output is not very readable
256perl v5.36.0 2023-01-20 Pod::Constants(3)