1Pod::Simple(3) User Contributed Perl Documentation Pod::Simple(3)
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6 Pod::Simple - framework for parsing Pod
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9 TODO
10
12 Pod::Simple is a Perl library for parsing text in the Pod ("plain old
13 documentation") markup language that is typically used for writing
14 documentation for Perl and for Perl modules. The Pod format is
15 explained in perlpod; the most common formatter is called "perldoc".
16 Be sure to read "ENCODING" if your Pod contains non-ASCII characters.
18 Pod formatters can use Pod::Simple to parse Pod documents and render
20 them into plain text, HTML, or any number of other formats. Typically,
21 such formatters will be subclasses of Pod::Simple, and so they will
22 inherit its methods, like "parse_file". But note that Pod::Simple
23 doesn't understand and properly parse Perl itself, so if you have a
24 file which contains a Perl program that has a multi-line quoted string
25 which has lines that look like pod, Pod::Simple will treat them as pod.
26 This can be avoided if the file makes these into indented here
27 documents instead.
28 If you're reading this document just because you have a Pod-processing
30 subclass that you want to use, this document (plus the documentation
31 for the subclass) is probably all you need to read.
32 If you're reading this document because you want to write a formatter
34 subclass, continue reading it and then read Pod::Simple::Subclassing,
35 and then possibly even read perlpodspec (some of which is for parser-
36 writers, but much of which is notes to formatter-writers).
37
39 "$parser = SomeClass->new();"
40 This returns a new parser object, where "SomeClass" is a subclass
41 of Pod::Simple.
42 "$parser->output_fh( *OUT );"
44 This sets the filehandle that $parser's output will be written to.
45 You can pass *STDOUT or *STDERR, otherwise you should probably do
46 something like this:
47 my $outfile = "output.txt";
49 open TXTOUT, ">$outfile" or die "Can't write to $outfile: $!";
50 $parser->output_fh(*TXTOUT);
51 ...before you call one of the "$parser->parse_whatever" methods.
53 "$parser->output_string( \$somestring );"
55 This sets the string that $parser's output will be sent to, instead
56 of any filehandle.
57 "$parser->parse_file( $some_filename );"
59 "$parser->parse_file( *INPUT_FH );"
60 This reads the Pod content of the file (or filehandle) that you
61 specify, and processes it with that $parser object, according to
62 however $parser's class works, and according to whatever parser
63 options you have set up for this $parser object.
64 "$parser->parse_string_document( $all_content );"
66 This works just like "parse_file" except that it reads the Pod
67 content not from a file, but from a string that you have already in
68 memory.
69 "$parser->parse_lines( ...@lines..., undef );"
71 This processes the lines in @lines (where each list item must be a
72 defined value, and must contain exactly one line of content -- so
73 no items like "foo\nbar" are allowed). The final "undef" is used
74 to indicate the end of document being parsed.
75 The other "parser_whatever" methods are meant to be called only
77 once per $parser object; but "parse_lines" can be called as many
78 times per $parser object as you want, as long as the last call (and
79 only the last call) ends with an "undef" value.
80 "$parser->content_seen"
82 This returns true only if there has been any real content seen for
83 this document. Returns false in cases where the document contains
84 content, but does not make use of any Pod markup.
85 "SomeClass->filter( $filename );"
87 "SomeClass->filter( *INPUT_FH );"
88 "SomeClass->filter( \$document_content );"
89 This is a shortcut method for creating a new parser object, setting
90 the output handle to STDOUT, and then processing the specified file
91 (or filehandle, or in-memory document). This is handy for one-
92 liners like this:
93 perl -MPod::Simple::Text -e "Pod::Simple::Text->filter('thingy.pod')"
95
97 Some of these methods might be of interest to general users, as well as
98 of interest to formatter-writers.
99 Note that the general pattern here is that the accessor-methods read
101 the attribute's value with "$value = $parser->attribute" and set the
102 attribute's value with "$parser->attribute(newvalue)". For each
103 accessor, I typically only mention one syntax or another, based on
104 which I think you are actually most likely to use.
105 "$parser->parse_characters( SOMEVALUE )"
107 The Pod parser normally expects to read octets and to convert those
108 octets to characters based on the "=encoding" declaration in the
109 Pod source. Set this option to a true value to indicate that the
110 Pod source is already a Perl character stream. This tells the
111 parser to ignore any "=encoding" command and to skip all the code
112 paths involving decoding octets.
113 "$parser->no_whining( SOMEVALUE )"
115 If you set this attribute to a true value, you will suppress the
116 parser's complaints about irregularities in the Pod coding. By
117 default, this attribute's value is false, meaning that
118 irregularities will be reported.
119 Note that turning this attribute to true won't suppress one or two
121 kinds of complaints about rarely occurring unrecoverable errors.
122 "$parser->no_errata_section( SOMEVALUE )"
124 If you set this attribute to a true value, you will stop the parser
125 from generating a "POD ERRORS" section at the end of the document.
126 By default, this attribute's value is false, meaning that an errata
127 section will be generated, as necessary.
128 "$parser->complain_stderr( SOMEVALUE )"
130 If you set this attribute to a true value, it will send reports of
131 parsing errors to STDERR. By default, this attribute's value is
132 false, meaning that no output is sent to STDERR.
133 Setting "complain_stderr" also sets "no_errata_section".
135 "$parser->source_filename"
137 This returns the filename that this parser object was set to read
138 from.
139 "$parser->doc_has_started"
141 This returns true if $parser has read from a source, and has seen
142 Pod content in it.
143 "$parser->source_dead"
145 This returns true if $parser has read from a source, and come to
146 the end of that source.
147 "$parser->strip_verbatim_indent( SOMEVALUE )"
149 The perlpod spec for a Verbatim paragraph is "It should be
150 reproduced exactly...", which means that the whitespace you've used
151 to indent your verbatim blocks will be preserved in the output.
152 This can be annoying for outputs such as HTML, where that
153 whitespace will remain in front of every line. It's an unfortunate
154 case where syntax is turned into semantics.
155 If the POD you're parsing adheres to a consistent indentation
157 policy, you can have such indentation stripped from the beginning
158 of every line of your verbatim blocks. This method tells
159 Pod::Simple what to strip. For two-space indents, you'd use:
160 $parser->strip_verbatim_indent(' ');
162 For tab indents, you'd use a tab character:
164 $parser->strip_verbatim_indent("\t");
166 If the POD is inconsistent about the indentation of verbatim
168 blocks, but you have figured out a heuristic to determine how much
169 a particular verbatim block is indented, you can pass a code
170 reference instead. The code reference will be executed with one
171 argument, an array reference of all the lines in the verbatim
172 block, and should return the value to be stripped from each line.
173 For example, if you decide that you're fine to use the first line
174 of the verbatim block to set the standard for indentation of the
175 rest of the block, you can look at the first line and return the
176 appropriate value, like so:
177 $new->strip_verbatim_indent(sub {
179 my $lines = shift;
180 (my $indent = $lines->[0]) =~ s/\S.*//;
181 return $indent;
182 });
183 If you'd rather treat each line individually, you can do that, too,
185 by just transforming them in-place in the code reference and
186 returning "undef". Say that you don't want any lines indented. You
187 can do something like this:
188 $new->strip_verbatim_indent(sub {
190 my $lines = shift;
191 sub { s/^\s+// for @{ $lines },
192 return undef;
193 });
194 "$parser->expand_verbatim_tabs( n )"
196 Default: 8
197 If after any stripping of indentation in verbatim blocks, there
199 remain tabs, this method call indicates what to do with them. 0
200 means leave them as tabs, any other number indicates that each tab
201 is to be translated so as to have tab stops every "n" columns.
202 This is independent of other methods (except that it operates after
204 any verbatim input stripping is done).
205 Like the other methods, the input parameter is not checked for
207 validity. "undef" or containing non-digits has the same effect as
208 8.
209
211 "$parser->abandon_output_fh()"
212 Cancel output to the file handle. Any POD read by the $parser is
213 not effected.
214 "$parser->abandon_output_string()"
216 Cancel output to the output string. Any POD read by the $parser is
217 not effected.
218 "$parser->accept_code( @codes )"
220 Alias for accept_codes.
221 "$parser->accept_codes( @codes )"
223 Allows $parser to accept a list of "Formatting Codes" in perlpod.
224 This can be used to implement user-defined codes.
225 "$parser->accept_directive_as_data( @directives )"
227 Allows $parser to accept a list of directives for data paragraphs.
228 A directive is the label of a "Command Paragraph" in perlpod. A
229 data paragraph is one delimited by "=begin/=for/=end" directives.
230 This can be used to implement user-defined directives.
231 "$parser->accept_directive_as_processed( @directives )"
233 Allows $parser to accept a list of directives for processed
234 paragraphs. A directive is the label of a "Command Paragraph" in
235 perlpod. A processed paragraph is also known as "Ordinary
236 Paragraph" in perlpod. This can be used to implement user-defined
237 directives.
238 "$parser->accept_directive_as_verbatim( @directives )"
240 Allows $parser to accept a list of directives for "Verbatim
241 Paragraph" in perlpod. A directive is the label of a "Command
242 Paragraph" in perlpod. This can be used to implement user-defined
243 directives.
244 "$parser->accept_target( @targets )"
246 Alias for accept_targets.
247 "$parser->accept_target_as_text( @targets )"
249 Alias for accept_targets_as_text.
250 "$parser->accept_targets( @targets )"
252 Accepts targets for "=begin/=for/=end" sections of the POD.
253 "$parser->accept_targets_as_text( @targets )"
255 Accepts targets for "=begin/=for/=end" sections that should be
256 parsed as POD. For details, see "About Data Paragraphs" in
257 perlpodspec.
258 "$parser->any_errata_seen()"
260 Used to check if any errata was seen.
261 Example:
263 die "too many errors\n" if $parser->any_errata_seen();
265 "$parser->errata_seen()"
267 Returns a hash reference of all errata seen, both whines and
268 screams. The hash reference's keys are the line number and the
269 value is an array reference of the errors for that line.
270 Example:
272 if ( $parser->any_errata_seen() ) {
274 $logger->log( $parser->errata_seen() );
275 }
276 "$parser->detected_encoding()"
278 Return the encoding corresponding to "=encoding", but only if the
279 encoding was recognized and handled.
280 "$parser->encoding()"
282 Return encoding of the document, even if the encoding is not
283 correctly handled.
284 "$parser->parse_from_file( $source, $to )"
286 Parses from $source file to $to file. Similar to "parse_from_file"
287 in Pod::Parser.
288 "$parser->scream( @error_messages )"
290 Log an error that can't be ignored.
291 "$parser->unaccept_code( @codes )"
293 Alias for unaccept_codes.
294 "$parser->unaccept_codes( @codes )"
296 Removes @codes as valid codes for the parse.
297 "$parser->unaccept_directive( @directives )"
299 Alias for unaccept_directives.
300 "$parser->unaccept_directives( @directives )"
302 Removes @directives as valid directives for the parse.
303 "$parser->unaccept_target( @targets )"
305 Alias for unaccept_targets.
306 "$parser->unaccept_targets( @targets )"
308 Removes @targets as valid targets for the parse.
309 "$parser->version_report()"
311 Returns a string describing the version.
312 "$parser->whine( @error_messages )"
314 Log an error unless "$parser->no_whining( TRUE );".
315
317 The Pod::Simple parser expects to read octets. The parser will decode
318 the octets into Perl's internal character string representation using
319 the value of the "=encoding" declaration in the POD source.
320 If the POD source does not include an "=encoding" declaration, the
322 parser will attempt to guess the encoding (selecting one of UTF-8 or CP
323 1252) by examining the first non-ASCII bytes and applying the heuristic
324 described in perlpodspec. (If the POD source contains only ASCII
325 bytes, the encoding is assumed to be ASCII.)
326 If you set the "parse_characters" option to a true value the parser
328 will expect characters rather than octets; will ignore any "=encoding";
329 and will make no attempt to decode the input.
330
332 Pod::Simple::Subclassing
333 perlpod
335 perlpodspec
337 Pod::Escapes
339 perldoc
341
343 Questions or discussion about POD and Pod::Simple should be sent to the
344 pod-people@perl.org mail list. Send an empty email to
345 pod-people-subscribe@perl.org to subscribe.
346 This module is managed in an open GitHub repository,
348 <https://github.com/perl-pod/pod-simple/>. Feel free to fork and
349 contribute, or to clone <https://github.com/perl-pod/pod-simple.git>
350 and send patches!
351 Please use <https://github.com/perl-pod/pod-simple/issues/new> to file
353 a bug report.
354
356 Copyright (c) 2002 Sean M. Burke.
357 This library is free software; you can redistribute it and/or modify it
359 under the same terms as Perl itself.
360 This program is distributed in the hope that it will be useful, but
362 without any warranty; without even the implied warranty of
363 merchantability or fitness for a particular purpose.
364
366 Pod::Simple was created by Sean M. Burke <sburke@cpan.org>. But don't
367 bother him, he's retired.
368 Pod::Simple is maintained by:
370 • Allison Randal "allison@perl.org"
372 • Hans Dieter Pearcey "hdp@cpan.org"
374 • David E. Wheeler "dwheeler@cpan.org"
376 • Karl Williamson "khw@cpan.org"
378 Documentation has been contributed by:
380 • Gabor Szabo "szabgab@gmail.com"
382 • Shawn H Corey "SHCOREY at cpan.org"
384perl v5.38.0 2023-07-21 Pod::Simple(3)