1Getopt::Lucid(3) User Contributed Perl Documentation Getopt::Lucid(3)
2
6 Getopt::Lucid - Clear, readable syntax for command line processing
7
9 version 1.10
10
12 use Getopt::Lucid qw( :all );
13 # basic option specifications with aliases
15 @specs = (
17 Switch("version|V"),
18 Counter("verbose|v"),
19 Param("config|C"),
20 List("lib|l|I"),
21 Keypair("define"),
22 Switch("help|h")
23 );
24 $opt = Getopt::Lucid->getopt( \@specs )->validate;
26 $verbosity = $opt->get_verbose;
28 @libs = $opt->get_lib;
29 %defs = $opt->get_define;
30 %all_options = $opt->options;
32 # advanced option specifications
34 @adv_spec = (
36 Param("input"),
37 Param("mode")->default("tcp"), # defaults
38 Param("host")->needs("port"), # dependencies
39 Param("port")->valid(qr/\d+/), # regex validation
40 Param("config")->valid(sub { -r }),# custom validation
41 Param("help")->anycase, # case insensitivity
42 );
43 $opt = Getopt::Lucid->getopt( \@adv_spec );
44 $opt->validate({ 'requires' => ['input'] });
45 # example with a config file
47 $opt = Getopt::Lucid->getopt( \@adv_spec );
49 use Config::Std;
50 if ( -r $opt->get_config ) {
51 read_config( $opt->get_config() => my %config_hash );
52 $opt->merge_defaults( $config_hash{''} );
53 }
54
56 The goal of this module is providing good code readability and clarity
57 of intent for command-line option processing. While readability is a
58 subjective standard, Getopt::Lucid relies on a more verbose, plain-
59 English option specification as compared against the more symbolic
60 approach of Getopt::Long. Key features include:
61 • Five option types: switches, counters, parameters, lists, and key
63 pairs
64 • Three option styles: long, short (including bundled), and bare
66 (without dashes)
67 • Specification of defaults, required options and option dependencies
69 • Validation of options with regexes or subroutines
71 • Negation of options on the command line
73 • Support for parsing any array, not just the default @ARGV
75 • Incorporation of external defaults (e.g. from a config file) with
77 user control of precedence
78
80 Option Styles, Naming and "Strictness"
81 Getopt::Lucid support three kinds of option styles: long-style
82 ("--foo"), short-style ("-f") and bareword style ("foo"). Short-style
83 options are automatically unbundled during command line processing if a
84 single dash is followed by more than one letter (e.g. "-xzf" becomes
85 "-x -z -f" ).
86 Each option is identified in the specification with a string consisting
88 of the option "name" followed by zero or more "aliases", with any alias
89 (and each subsequent alias) separated by a vertical bar character.
90 E.g.:
91 "lib|l|I" means name "lib", alias "l" and alias "I"
93 Names and aliases must begin with an alphanumeric character, but
95 subsequently may also include both underscore and dash. (E.g. both
96 "input-file" and "input_file" are valid.) While names and aliases are
97 interchangeable when provided on the command line, the "name" portion
98 is used with the accessors for each option (see "Accessors and
99 Mutators").
100 Any of the names and aliases in the specification may be given in any
102 of the three styles. By default, Getopt::Lucid works in "magic" mode,
103 in which option names or aliases may be specified with or without
104 leading dashes, and will be parsed from the command line whether or not
105 they have corresponding dashes. Single-character names or aliases may
106 be read with no dash, one dash or two dashes. Multi-character names or
107 aliases must have either no dashes or two dashes. E.g.:
108 • Both "foo" and "--foo" as names in the specification may be read
110 from the command line as either "--foo" or "foo"
111 • The specification name "f" may be read from the command line as
113 "--f", "-f", or just "f"
114 In practice, this means that the specification need not use dashes, but
116 if used on the command line, they will be treated appropriately.
117 Alternatively, Getopt::Lucid can operate in "strict" mode by setting
119 the C<strict> parameter to a true value. In strict mode, option names
120 and aliases may still be specified in any of the three styles, but they
121 will only be parsed from the command line if they are used in exactly
122 the same style. E.g., given the name and alias "--help|-h", only
123 "--help" and "-h" are valid for use on the command line.
124 Option Specification Constructors
126 Options specifications are provided to Getopt::Lucid in an array.
127 Entries in the array must be created with one of several special
128 constructor functions that return a specification object. These
129 constructor functions may be imported either individually or as a group
130 using the import tag ":all" (e.g. "use Getopt::Lucid qw(:all);").
131 The form of the constructor is:
133 TYPE( NAME_ARGUMENT );
135 The constructor function name indicates the type of option. The name
137 argument is a string with the names and aliases separated by vertical
138 bar characters.
139 The five option specification constructors are:
141 Switch()
143 A true/false value. Defaults to false. The appearance of an option of
145 this type on the command line sets it to true.
146 Counter()
148 A numerical counter. Defaults to 0. The appearance of an option of
150 this type on the command line increments the counter by one.
151 Param()
153 A variable taking an argument. Defaults to "" (the empty string).
155 When an option of this type appears on the command line, the value of
156 the option is set in one of two ways -- appended with an equals sign or
157 from the next argument on the command line:
158 --name=value
160 --name value
161 In the case where white space is used to separate the option name and
163 the value, if the value looks like an option, an exception will be
164 thrown:
165 --name --value # throws an exception
167 List()
169 This is like Param() but arguments are pushed onto a list. The default
171 list is empty.
172 Keypair()
174 A variable taking an argument pair, which are added to a hash.
176 Arguments are handled as with Param(), but the argument itself must
177 have a key and value joined by an equals sign.
178 --name=key=value
180 --name key=value
181 Option modifiers
183 An option specification can be further modified with the following
184 methods, each of which return the object modified so that modifier
185 chaining is possible. E.g.:
186 @spec = (
188 Param("input")->default("/dev/random")->needs("output"),
189 Param("output")->default("/dev/null"),
190 );
191 valid()
193 Sets the validation parameter(s) for an option.
195 @spec = (
197 Param("port")->valid(qr/\d+/), # regex validation
198 Param("config")->valid(sub { -r }), # custom validation
199 Keypair("define")
200 ->valid(\&_valid_key, \&valid_value), # keypairs take two
201 );
202 See the "Validation" section, below, for more.
204 default()
206 Changes the default for the option to the argument(s) of default().
208 List and hashes can take either a list or a reference to an array or
209 hash, respectively.
210 @spec = (
212 Switch("debug")->default(1),
213 Counter("verbose")->default(3),
214 Param("config")->default("/etc/profile"),
215 List("dirs")->default(qw( /var /home )),
216 Keypair("define")->default( arch => "i386" ),
217 );
218 needs()
220 Takes as an argument a list of option names or aliases of dependencies.
222 If the option this modifies appears on the command line, each of the
223 options given as an argument must appear on the command line as well or
224 an exception is thrown.
225 @spec = (
227 Param("input")->needs("output"),
228 Param("output"),
229 );
230 anycase()
232 Indicates that the associated option names/aliases may appear on the
234 command line in lowercase, uppercase, or any mixture of the two. No
235 argument is needed.
236 @spec = (
238 Switch("help|h")->anycase(), # "Help", "HELP", etc.
239 );
240 doc()
242 Sets the documentation string for an option.
244 @spec = (
246 Param("output")->doc("write output to the specified file"),
247 );
248 This string shows up in the "usage" method.
250 Validation
252 Validation happens in two stages. First, individual parameters may
253 have validation criteria added to them. Second, the parsed options
254 object may be validated by checking that all requirements collectively
255 are met.
256 Parameter validation
258 The Param, List, and Keypair option types may be provided an optional
260 validation specification. Values provided on the command line will be
261 validated according to the specification or an exception will be
262 thrown.
263 A validation specification can be either a regular expression, or a
265 reference to a subroutine. Keypairs take up to two validation
266 specifiers. The first is applied to keys and the second is applied to
267 values; either can be left undef to ignore validation. (More complex
268 validation of specific values for specific keys must be done manually.)
269 Validation is also applied to default values provided via the default()
271 modifier or later modified with "append_defaults", "merge_defaults", or
272 "replace_defaults". This ensures internal consistency.
273 If no default is explicitly provided, validation is only applied if the
275 option appears on the command line. (In other words, the built-in
276 defaults are always considered valid if the option does not appear.)
277 If this is not desired, the "required" option to the "validate" method
278 should be used to force users to provide an explicit value.
279 # Must be provided and is thus always validated
281 @spec = ( Param("width")->valid(qr/\d+/) );
282 $opt = Getopt::Lucid->getopt(\@spec);
283 $opt->validate( {requires => ['width']} );
284 For validation subroutines, the value found on the command line is
286 passed as the first element of @_, and $_ is also set equal to the
287 first element. (N.B. Changing $_ will not change the value that is
288 captured.) The value validates if the subroutine returns a true value.
289 For validation with regular expressions, consider using Regexp::Common
291 for a ready library of validation options.
292 Older versions of Getopt::Lucid used validation arguments provided in
294 the Spec constructor. This is still supported, but is deprecated and
295 discouraged. It may be removed in a future version of Getopt::Lucid.
296 # deprecated
298 Param("height", qr/\d+/)
299 Options object validation
301 The "validate" method should be called on the result of "getopt". This
303 will check that all parameter prerequisites defined by "needs" have
304 been met. It also takes a hashref of arguments. The optional
305 "requires" argument gives an arrayref of parameters that must exist.
306 The reason that object validation is done separate from "getopt" is to
308 allow for better control over different options that might be required
309 or to allow some dependencies (i.e. from "needs") to be met via a
310 configuration file.
311 @spec = (
313 Param("action")->needs(qw/user password/),
314 Param("user"),
315 Param("password"),
316 );
317 $opt = Getopt::Lucid->getopt(\@spec);
318 $opt->merge_defaults( read_config() ); # provides 'user' & 'password'
319 $opt->validate({requires => ['action']});
320 Parsing the Command Line
322 Technically, Getopt::Lucid scans an array for command line options, not
323 a command-line string. By default, this array is @ARGV (though other
324 arrays can be used -- see new()), which is typically provided by the
325 operating system according to system-specific rules.
326 When Getopt::Lucid processes the array, it scans the array in order,
328 removing any specified command line options and any associated
329 arguments, and leaving behind any unrecognized elements in the array.
330 If an element consisting solely of two-dashes ("--") is found, array
331 scanning is terminated at that point. Any options found during
332 scanning are applied in order. E.g.:
333 @ARGV = qw( --lib /tmp --lib /var );
335 my $opt = Getopt::Lucid->getopt( [ List("lib") ] );
336 print join ", " $opt->lib;
337 # prints "/tmp, /var"
338 If an element encountered in processing begins with a dash, but is not
340 recognized as a short-form or long-form option name or alias, an
341 exception will be thrown.
342 Negation
344 Getopt::Lucid also supports negating options. Options are negated if
345 the option is specified with "no-" or "--no-" prefixed to a name or
346 alias. By default, negation clears the option: Switch and Counter
347 options are set to zero; Param options are set to ""; List and Keypair
348 options are set to an empty list and empty hash, respectively. For List
349 and Keypair options, it is also possible to negate a specific list
350 element or hash key by placing an equals sign and the list element or
351 key immediately after the option name:
352 --no-lib=/tmp --no-define=arch
354 # removes "/tmp" from lib and the "arch" key from define
355 As with all options, negation is processed in order, allowing a "reset"
357 in the middle of command line processing. This may be useful for those
358 using command aliases who wish to "switch off" options in the alias.
359 E.g, in Unix:
360 $ alias wibble = wibble.pl --verbose
362 $ wibble --no-verbose
363 # @ARGV would contain ( "--verbose", "--no-verbose" )
365 This also may have applications in post-processing configuration files
367 (see "Managing Defaults and Config Files").
368 Accessors and Mutators
370 After processing the command-line array, the values of the options may
371 be read or modified using accessors/mutators of the form "get_NAME" and
372 "set_NAME", where NAME represents the option name in the specification
373 without any leading dashes. E.g.
374 @spec = (
376 Switch("--test|-t"),
377 List("--lib|-L"),
378 Keypair("--define|-D"),
379 );
380 $opt = Getopt::Lucid->getopt( \@spec );
382 print $opt->get_test ? "True" : "False";
383 $opt->set_test(1);
384 For option names with dashes, underscores should be substituted in the
386 accessor calls. E.g.
387 @spec = (
389 Param("--input-file|-i")
390 );
391 $opt = Getopt::Lucid->getopt( \@spec );
393 print $opt->get_input_file;
394 This can create an ambiguous case if a similar option exists with
396 underscores in place of dashes. (E.g. "input_file" and "input-file".)
397 Users can safely avoid these problems by choosing to use either dashes
398 or underscores exclusively and not mixing the two styles.
399 List and Keypair options are returned as flattened lists:
401 my @lib = $opt->get_lib;
403 my %define = $opt->get_define;
404 Using the "set_NAME" mutator is not recommended and should be used with
406 caution. No validation is performed and changes will be lost if the
407 results of processing the command line array are recomputed (e.g, such
408 as occurs if new defaults are applied). List and Keypair options
409 mutators take a list, not references.
410 Managing Defaults and Config Files
412 A typical problem for command-line option processing is the precedence
413 relationship between default option values specified within the
414 program, default option values stored in a configuration file or in
415 environment variables, and option values specified on the command-line,
416 particularly when the command-line specifies an alternate configuration
417 file.
418 Getopt::Lucid takes the following approach to this problem:
420 • Initial default values may be specified as part of the option
422 specification (using the default() modifier)
423 • Default values from the option specification may be modified or
425 replaced entirely with default values provided in an external hash
426 (such as from a standard config file or environment variables)
427 • When the command-line array is processed, options and their
429 arguments are stored in the order they appeared in the command-line
430 array
431 • The stored options are applied in-order to modify or replace the
433 set of "current" default option values
434 • If default values are subsequently changed (such as from an
436 alternative configuration file), the stored options are re-applied
437 in-order to the new set of default option values
438 With this approach, the resulting option set is always the result of
440 applying options (or negations) from the command-line array to a set of
441 default-values. Users have complete freedom to apply whatever
442 precedence rules they wish to the default values and may even change
443 default values after the command-line array is processed without losing
444 the options given on the command line.
445 Getopt::Lucid provides several functions to assist in manipulating
447 default values:
448 • merge_defaults() -- new defaults overwrite any matching, existing
450 defaults. KeyPairs hashes and List arrays are replaced entirely
451 with new defaults
452 • append_defaults() -- new defaults overwrite any matching, existing
454 defaults, except for Counter and List options, which have the new
455 defaults added and appended, respectively, and KeyPair options,
456 which are flattened into any existing default hash
457 • replace_defaults() -- new defaults replace existing defaults; any
459 options not provided in the new defaults are reset to zero/empty,
460 ignoring any default given in the option specification
461 • reset_defaults() -- returns defaults to values given in the options
463 specification
464 Exceptions and Error Handling
466 Getopt::Lucid uses Exception::Class for exceptions. When a major error
467 occurs, Getopt::Lucid will die and throw one of three Exception::Class
468 subclasses:
469 • "Getopt::Lucid::Exception::Usage" -- thrown when Getopt::Lucid
471 methods are called incorrectly
472 • "Getopt::Lucid::Exception::Spec" -- thrown when the specification
474 array contains incorrect or invalid data
475 • "Getopt::Lucid::Exception::ARGV" -- thrown when the command-line is
477 processed and fails to pass specified validation, requirements, or
478 is otherwise determined to be invalid
479 These exceptions may be caught using an "eval" block and allow the
481 calling program to respond differently to each class of exception.
482 Ambiguous Cases and Gotchas
484 One-character aliases and "anycase"
485 @spec = (
487 Counter("verbose|v")->anycase,
488 Switch("version|V")->anycase,
489 );
490 Consider the spec above. By specifying "anycase" on these, "verbose",
492 "Verbose", "VERBOSE" are all acceptable, as are "version", "Version"
493 and so on. (Including long-form versions of these, too, if "magic"
494 mode is used.) However, what if the command line has "-v" or even "-v
495 -V"? In this case, the rule is that exact case matches are used before
496 case-insensitive matches are searched. Thus, "-v" can only match
497 "verbose", despite the "anycase" modification, and likewise "-V" can
498 only match "version".
499 Identical names except for dashes and underscores
501 @spec = (
503 Param("input-file"),
504 Switch("input_file"),
505 );
506 Consider the spec above. These are two, separate, valid options, but a
508 call to the accessor "get_input_file" is ambiguous and may return
509 either option, depending on which first satisfies a "fuzzy-matching"
510 algorithm inside the accessor code. Avoid identical names with mixed
511 dash and underscore styles.
512
514 new()
515 $opt = Getopt::Lucid->new( \@option_spec );
516 $opt = Getopt::Lucid->new( \@option_spec, \%parameters );
517 $opt = Getopt::Lucid->new( \@option_spec, \@option_array );
518 $opt = Getopt::Lucid->new( \@option_spec, \@option_array, \%parameters );
519 Creates a new Getopt::Lucid object. An array reference to an option
521 spec is required as an argument. (See "USAGE" for a description of the
522 object spec). By default, objects will be set to read @ARGV for
523 command line options. An optional second argument with a reference to
524 an array will use that array for option processing instead. The final
525 argument may be a hashref of parameters. The only valid parameter
526 currently is:
527 • strict -- enables strict mode when true
529 For typical cases, users will likely prefer to call "getopt" instead,
531 which creates a new object and parses the command line with a single
532 function call.
533 validate()
535 $opt->validate();
536 $opt->validate( \%arguments );
537 Takes an optional argument hashref, validates that all requirements and
539 prerequisites are met or throws an error. Valid argument keys are:
540 • "requires" -- an arrayref of options that must exist in the options
542 object.
543 This method returns the object for convenient chaining:
545 $opt = Getopt::Lucid->getopt(\@spec)->validate;
547 append_defaults()
549 %options = append_defaults( %config_hash );
550 %options = append_defaults( \%config_hash );
551 Takes a hash or hash reference of new default values, modifies the
553 stored defaults, recalculates the result of processing the command line
554 with the revised defaults, and returns a hash with the resulting
555 options. Each key/value pair in the passed hash is added to the stored
556 defaults. For Switch and Param options, the value in the passed hash
557 will overwrite any preexisting value. For Counter options, the value
558 is added to any preexisting value. For List options, the value (or
559 values, if the value is an array reference) will be pushed onto the end
560 of the list of existing values. For Keypair options, the key/value
561 pairs will be added to the existing hash, overwriting existing
562 key/value pairs (just like merging two hashes). Keys which are not
563 valid names from the options specification will be ignored.
564 defaults()
566 %defaults = $opt->defaults();
567 Returns a hash containing current default values. Keys are names from
569 the option specification (without any leading dashes). These defaults
570 represent the baseline values that are modified by the parsed command
571 line options.
572 getopt()
574 $opt = Getopt::Lucid->getopt( \@option_spec );
575 $opt = Getopt::Lucid->getopt( \@option_spec, \@option_array );
576 $opt->getopt();
577 Parses the command line array (@ARGV by default). When called as a
579 class function, "getopt" takes the same arguments as "new", calls "new"
580 to create an object before parsing the command line, and returns the
581 new object. When called as an object method, it takes no arguments and
582 returns itself.
583 For convenience, C<getopts()> is a alias for C<getopt()>.
585 merge_defaults()
587 %options = merge_defaults( %config_hash );
588 %options = merge_defaults( \%config_hash );
589 Takes a hash or hash reference of new default values, modifies the
591 stored defaults, recalculates the result of processing the command line
592 with the revised defaults, and returns a hash with the resulting
593 options. Each key/value pair in the passed hash is added to the stored
594 defaults, overwriting any preexisting value. Keys which are not valid
595 names from the options specification will be ignored.
596 names()
598 @names = $opt->names();
599 Returns the list of names in the options specification. Each name
601 represents a key in the hash of options provided by "options".
602 options()
604 %options = $opt->options();
605 Returns a deep copy of the options hash. Before "getopt" is called,
607 its behavior is undefined. After "getopt" is called, this will return
608 the result of modifying the defaults with the results of command line
609 processing.
610 replace_defaults()
612 %options = replace_defaults( %config_hash );
613 %options = replace_defaults( \%config_hash );
614 Takes a hash or hash reference of new default values, replaces the
616 stored defaults, recalculates the result of processing the command line
617 with the revised defaults, and returns a hash with the resulting
618 options. Each key/value pair in the passed hash replaces existing
619 defaults, including those given in the option specifications. Keys
620 which are not valid names from the option specification will be
621 ignored.
622 reset_defaults()
624 %options = reset_defaults();
625 Resets the stored defaults to the original values from the options
627 specification, recalculates the result of processing the command line
628 with the restored defaults, and returns a hash with the resulting
629 options. This undoes the effect of a "merge_defaults" or
630 "add_defaults" call.
631 usage()
633 Returns a string of usage information derived from the options spec,
634 including any "doc" modifiers. Because invalid options throw
635 exceptions, if you want to provide usage, you should separately invoke
636 "new" and "getopt"
637 my $opt = Getopt::Lucid->new( \@spec );
639 eval { $opt->getopt() };
640 if ($@) {
641 print "$@\n" && print $opt->usage and exit 1
642 if ref $@ eq 'Getopt::Lucid::Exception::ARGV';
643 ref $@ ? $@->rethrow : die $@;
644 }
645
647 In 1.00, the following API changes have been made:
648 • new() now takes an optional hashref of parameters as the last
650 argument
651 • The global $STRICT variable has been replaced with a per-object
653 parameter "strict"
654 • The "required" modifier has been removed and a new "validate"
656 method has been added to facilitate late/custom checks of required
657 options
658
660 • Config::Tiny
661 • Config::Simple
663 • Config::Std
665 • Getopt::Long
667 • Regexp::Common
669
671 Please report any bugs or feature using the CPAN Request Tracker. Bugs
672 can be submitted through the web interface at
673 <http://rt.cpan.org/Dist/Display.html?Queue=Getopt-Lucid>
674 When submitting a bug or request, please include a test-file or a patch
676 to an existing test-file that illustrates the bug or desired feature.
677
679 Bugs / Feature Requests
680 Please report any bugs or feature requests through the issue tracker at
681 <https://github.com/dagolden/Getopt-Lucid/issues>. You will be
682 notified automatically of any progress on your issue.
683 Source Code
685 This is open source software. The code repository is available for
686 public review and contribution under the terms of the license.
687 <https://github.com/dagolden/Getopt-Lucid>
689 git clone https://github.com/dagolden/Getopt-Lucid.git
691
693 David Golden <dagolden@cpan.org>
694
696 • Chris White <cxwembedded@gmail.com>
697 • David Golden <xdg@xdg.me>
699 • David Precious <davidp@preshweb.co.uk>
701 • James E Keenan <jkeenan@cpan.org>
703 • Kevin McGrath <kmcgrath@cpan.org>
705 • Nova Patch <patch@cpan.org>
707 • Robert Bohne <rbo@cpan.org>
709 • thilp <thilp@thilp.net>
711
713 This software is Copyright (c) 2019 by David Golden.
714 This is free software, licensed under:
716 The Apache License, Version 2.0, January 2004
718perl v5.38.0 2023-07-20 Getopt::Lucid(3)