1Pod::Constants(3)     User Contributed Perl Documentation    Pod::Constants(3)
2
3
4

NAME

6       Pod::Constants - Include constants from POD
7

SYNOPSIS

9        our ($myvar, $VERSION, @myarray, $html, %myhash);
10
11        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
18        =head2 Pod Section Name
19
20        This string will be loaded into $myvar
21
22        =head2 Version
23
24        # 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
29        =head2 Some list
30
31        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
35        =head2 Some hash
36
37        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
43        =head2 %myhash's value after the above:
44
45           ( key1 => "Some value (this will go into the hash)",
46             var2 => "Some Other value (so will this)"          )
47
48        =begin html <p>This text will be in $html</p>
49
50        =cut
51

DESCRIPTION

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
57       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
62   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
68       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

FUNCTIONS

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
77       The form of @args is HOOK => $where.
78
79       $where may be a scalar reference, in which case the contents of the POD
80       section called "HOOK" will be loaded into $where.
81
82       $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
86       $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
91       $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
95       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
102       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
106       Note that the supplied functions for array and hash splitting are
107       exactly equivalent to fairly simple Perl blocks:
108
109       Array:
110
111         HOOK => sub { @array = split /\n/, $_ }
112
113       Hash:
114
115         HOOK => sub {
116         %hash =
117             (map { map { s/^\s+|\s+$//g; $_ } split /=>/, $_ }
118               (grep m/^
119                   ( (?:[^=]|=[^>])+ )   # scan up to "=>"
120                   =>
121                   ( (?:[^=]|=[^>])+ =? )# don't allow more "=>"'s
122                   $/x, split /\n/, $_));
123         }
124
125       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
129       Here's the procedural equivalent:
130
131         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} = $value;
138            }
139         },
140
141   import_from_file($filename, @args)
142       Very similar to straight "import", but you specify the source filename
143       explicitly.
144
145   add_hook(NAME => value)
146       This function adds another hook, it is useful for dynamic updating of
147       parsing through the document.
148
149       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
152   delete_hook(@list)
153       Deletes the named hooks.  Companion function to add_hook
154
155   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
161       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
165       Below are some examples.
166

EXAMPLES

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
172   Example Makefile.PL
173        eval "use Pod::Constants";
174        ($Pod::Constants::VERSION >= 0.11)
175            or die <<EOF
176        ####
177        ####  ERROR: This module requires Pod::Constants 0.11 or
178        ####  higher to be installed.
179        ####
180        EOF
181
182        my ($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
193        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
203   Corresponding Module
204        =head1 NAME
205
206        MyTestModule - Demonstrate Pod::Constant's Makefile.PL usefulness
207
208        =head2 MODULE RELEASE
209
210        This is release 1.05 of this module.
211
212        =head2 DEPENDENCIES
213
214        The following modules are required to make this module:
215
216           Some::Module => 0.02
217
218        =head2 AUTHOR
219
220        Ima Twat <ima@twat.name>
221
222        =cut
223
224        our $VERSION;
225        use Pod::Constants -trim => 1,
226            'MODULE RELEASE' => sub { ($VERSION) = m/(\d+\.\d+) or die };
227

AUTHOR

229       Sam Vilain, <samv@cpan.org>
230
231       Maintained by Marius Gavrilescu, <marius@ieval.ro> since July 2015
232
234       Copyright (C) 2001, 2002, 2007 Sam Vilain. All Rights Reserved.
235
236       Copyright (C) 2015-2016 by Marius Gavrilescu <marius@ieval.ro>.
237
238       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
241       See the LICENSE file in the root of this distribution for a copy of the
242       Perl Artistic License, version 2.
243

BUGS/TODO

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
251       Would this be useful?
252
253        Pod::Constants::import(Foo::SECTION => \$myvar);
254
255       Debug output is not very readable
256
257
258
259perl v5.32.0                      2020-07-28                 Pod::Constants(3)
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