1Getopt::Long::DescriptiUvsee(r3)Contributed Perl DocumenGteattoipotn::Long::Descriptive(3)
2
6 Getopt::Long::Descriptive - Getopt::Long, but simpler and more powerful
7
9 version 0.109
10
12 use Getopt::Long::Descriptive;
13 my ($opt, $usage) = describe_options(
15 'my-program %o <some-arg>',
16 [ 'server|s=s', "the server to connect to", { required => 1 } ],
17 [ 'port|p=i', "the port to connect to", { default => 79 } ],
18 [],
19 [ 'verbose|v', "print extra stuff" ],
20 [ 'help', "print usage message and exit", { shortcircuit => 1 } ],
21 );
22 print($usage->text), exit if $opt->help;
24 Client->connect( $opt->server, $opt->port );
26 print "Connected!\n" if $opt->verbose;
28 ...and running "my-program --help" will produce:
30 my-program [-psv] [long options...] <some-arg>
32 -s --server the server to connect to
33 -p --port the port to connect to
34 -v --verbose print extra stuff
36 --help print usage message and exit
37
39 Getopt::Long::Descriptive is yet another Getopt library. It's built
40 atop Getopt::Long, and gets a lot of its features, but tries to avoid
41 making you think about its huge array of options.
42 It also provides usage (help) messages, data validation, and a few
44 other useful features.
45
47 Getopt::Long::Descriptive only exports one routine by default:
48 "describe_options". All GLD's exports are exported by Sub::Exporter.
49 describe_options
51 my ($opt, $usage) = describe_options($usage_desc, @opt_spec, \%arg);
52 This routine inspects @ARGV for options that match the supplied spec.
54 If all the options are valid then it returns the options given and an
55 object for generating usage messages; if not then it dies with an
56 explanation of what was wrong and a usage message.
57 The $opt object will be a dynamically-generated subclass of
59 Getopt::Long::Descriptive::Opts. In brief, each of the options in
60 @opt_spec becomes an accessor method on the object, using the first-
61 given name, with dashes converted to underscores. For more
62 information, see the documentation for the Opts class.
63 The $usage object will be a Getopt::Long::Descriptive::Usage object,
65 which provides a "text" method to get the text of the usage message and
66 "die" to die with it. For more methods and options, consults the
67 documentation for the Usage class.
68 $usage_desc
70 The $usage_desc parameter to "describe_options" is a "sprintf"-like
72 string that is used in generating the first line of the usage message.
73 It's a one-line summary of how the command is to be invoked. A typical
74 usage description might be:
75 $usage_desc = "%c %o <source> <desc>";
77 %c will be replaced with what Getopt::Long::Descriptive thinks is the
79 program name (it's computed from $0, see "prog_name").
80 %o will be replaced with a list of the short options, as well as the
82 text "[long options...]" if any have been defined.
83 The rest of the usage description can be used to summarize what
85 arguments are expected to follow the program's options, and is entirely
86 free-form.
87 Literal "%" characters will need to be written as "%%", just like with
89 "sprintf".
90 @opt_spec
92 The @opt_spec part of the args to "describe_options" is used to
94 configure option parsing and to produce the usage message. Each entry
95 in the list is an arrayref describing one option, like this:
96 @opt_spec = (
98 [ "verbose|V" => "be noisy" ],
99 [ "logfile=s" => "file to log to" ],
100 );
101 The first value in the arrayref is a Getopt::Long-style option
103 specification. In brief, they work like this: each one is a pipe-
104 delimited list of names, optionally followed by a type declaration.
105 Type declarations are '=x' or ':x', where "=" means a value is required
106 and ":" means it is optional. x may be 's' to indicate a string is
107 required, 'i' for an integer, or 'f' for a number with a fractional
108 part. The type spec may end in "@" to indicate that the option may
109 appear multiple times.
110 For more information on how these work, see the Getopt::Long
112 documentation.
113 The first name given should be the canonical name, as it will be used
115 as the accessor method on the $opt object. Dashes in the name will be
116 converted to underscores, and all letters will be lowercased. For this
117 reason, all options should generally have a long-form name.
118 The second value in the arrayref is a description of the option, for
120 use in the usage message.
121 Special Option Specifications
123 If the option specification (arrayref) is empty, it will have no effect
125 other than causing a blank line to appear in the usage message.
126 If the option specification contains only one element, it will be
128 printed in the usage message with no other effect. If the element is a
129 reference, its referent will be printed as-is. Otherwise, it will be
130 reformatted like other text in the usage message.
131 If the option specification contains a third element, it adds extra
133 constraints or modifiers to the interpretation and validation of the
134 value. These are the keys that may be present in that hashref, and how
135 they behave:
136 implies
138 implies => 'bar'
139 implies => [qw(foo bar)]
140 implies => { foo => 1, bar => 2 }
141 If option A has an "implies" entry, then if A is given, other
143 options will be enabled. The value may be a single option to set,
144 an arrayref of options to set, or a hashref of options to set to
145 specific values.
146 required
148 required => 1
149 If an option is required, failure to provide the option will result
151 in "describe_options" printing the usage message and exiting.
152 hidden
154 hidden => 1
155 This option will not show up in the usage text.
157 You can achieve the same behavior by using the string "hidden" for
159 the option's description.
160 one_of
162 one_of => \@subopt_specs
163 This is useful for a group of options that are related. Each
165 option spec is added to the list for normal parsing and validation.
166 Your option name will end up with a value of the name of the option
168 that was chosen. For example, given the following spec:
169 [ "mode" => hidden => { one_of => [
171 [ "get|g" => "get the value" ],
172 [ "set|s" => "set the value" ],
173 [ "delete" => "delete it" ],
174 ] } ],
175 No usage text for 'mode' will be displayed, but text for get, set,
177 and delete will be displayed.
178 If more than one of get, set, or delete is given, an error will be
180 thrown.
181 So, given the @opt_spec above, and an @ARGV of "('--get')", the
183 following would be true:
184 $opt->get == 1;
186 $opt->mode eq 'get';
188 Note: "get" would not be set if "mode" defaulted to 'get' and no
190 arguments were passed in.
191 Even though the option sub-specs for "one_of" are meant to be
193 'first class' specs, some options don't make sense with them, e.g.
194 "required".
195 As a further shorthand, you may specify "one_of" options using this
197 form:
198 [ mode => \@option_specs, \%constraints ]
200 shortcircuit
202 shortcircuit => 1
203 If this option is present no other options will be returned. Other
205 options present will be checked for proper types, but not for
206 constraints. This provides a way of specifying "--help" style
207 options.
208 Params::Validate
210 In addition, any constraint understood by Params::Validate may be
211 used.
212 For example, to accept positive integers:
214 [ 'max-iterations=i', "maximum number of iterations",
216 { callbacks => { positive => sub { shift() > 0 } } } ],
217 (Internally, all constraints are translated into Params::Validate
219 options or callbacks.)
220 %arg
222 The %arg to "describe_options" is optional. If the last parameter is a
224 hashref, it contains extra arguments to modify the way
225 "describe_options" works. Valid arguments are:
226 getopt_conf - an arrayref of strings, passed to Getopt::Long::Configure
228 show_defaults - a boolean which controls whether an option's default
229 value (if applicable) is shown as part of the usage message
230 (for backward compatibility this defaults to false)
231 prog_name
233 This routine, exported on demand, returns the basename of $0, grabbed
234 at compile-time. You can override this guess by calling
235 "prog_name($string)" yourself.
236
238 "-types"
239 Any of the Params::Validate type constants ("SCALAR", etc.) can be
240 imported as well. You can get all of them at once by importing
241 "-types".
242 "-all"
244 This import group will import "-type", "describe_options", and
245 "prog_name".
246
248 Getopt::Long::Descriptive uses Sub::Exporter to build and export the
249 "describe_options" routine. By writing a new class that extends
250 Getopt::Long::Descriptive, the behavior of the constructed
251 "describe_options" routine can be changed.
252 The following methods can be overridden:
254 usage_class
256 my $class = Getopt::Long::Descriptive->usage_class;
257 This returns the class to be used for constructing a Usage object, and
259 defaults to Getopt::Long::Descriptive::Usage.
260
262 • Getopt::Long
263 • Params::Validate
265
267 • Hans Dieter Pearcey <hdp@cpan.org>
268 • Ricardo Signes <rjbs@cpan.org>
270
272 • Arthur Axel 'fREW' Schmidt <frioux@gmail.com>
273 • Dave Rolsky <autarch@urth.org>
275 • Diab Jerius <djerius@cfa.harvard.edu>
277 • Hans Dieter Pearcey <hdp@pobox.com>
279 • Hans Dieter Pearcey <hdp@weftsoar.net>
281 • Harley Pig <harleypig@gmail.com>
283 • hdp@cpan.org <hdp@cpan.org@fc0e91e4-031c-0410-8307-be39b06d7656>
285 • Karen Etheridge <ether@cpan.org>
287 • Michael McClimon <michael@mcclimon.org>
289 • Niels Thykier <niels@thykier.net>
291 • Olaf Alders <olaf@wundersolutions.com>
293 • Ricardo Signes <rjbs@semiotic.systems>
295 • Roman Hubacek <roman.hubacek@centrum.cz>
297 • Smylers <SMYLERS@cpan.fsck.com>
299 • Thomas Neumann <blacky+perl@fluffbunny.de>
301 • zhouzhen1 <zhouzhen1@gmail.com>
303
305 This software is copyright (c) 2005 by Hans Dieter Pearcey.
306 This is free software; you can redistribute it and/or modify it under
308 the same terms as the Perl 5 programming language system itself.
309perl v5.32.1 2021-03-17 Getopt::Long::Descriptive(3)