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Getopt::Long::Descriptive(3) User Contributed Perl Documentation Getopt::Long::Descriptive(3)
NAME
Getopt::Long::Descriptive - Getopt::Long, but simpler and more powerful
VERSION
version 0.093
SYNOPSIS
use Getopt::Long::Descriptive;
my ($opt, $usage) = describe_options(
'my-program %o <some-arg>',
[ 'server|s=s', "the server to connect to" ],
[ 'port|p=i', "the port to connect to", { default => 79 } ],
[],
[ 'verbose|v', "print extra stuff" ],
[ 'help', "print usage message and exit" ],
);
print($usage->text), exit if $opt->help;
Client->connect( $opt->server, $opt->port );
print "Connected!\n" if $opt->verbose;
...and running "my-program --help" will produce:
my-program [-psv] [long options...] <some-arg>
-s --server the server to connect to
-p --port the port to connect to
-v --verbose print extra stuff
--help print usage message and exit
DESCRIPTION
Getopt::Long::Descriptive is yet another Getopt library. It's built atop Getopt::Long,
and gets a lot of its features, but tries to avoid making you think about its huge array
of options.
It also provides usage (help) messages, data validation, and a few other useful features.
FUNCTIONS
Getopt::Long::Descriptive only exports one routine by default: "describe_options". All
GLD's exports are exported by Sub::Exporter.
describe_options
my ($opt, $usage) = describe_options($usage_desc, @opt_spec, \%arg);
This routine inspects @ARGV returns the options given and a object for generating usage
messages.
The $opt object will be a dynamically-generated subclass of
Getopt::Long::Descriptive::Opts. In brief, each of the options in @opt_spec becomes an
accessor method on the object, using the first-given name, with dashes converted to
underscores. For more information, see the documentation for the Opts class.
The $usage object will be a Getopt::Long::Descriptive::Usage object, which provides a
"text" method to get the text of the usage message and "die" to die with it. For more
methods and options, consults the documentation for the Usage class.
$usage_desc
The $usage_desc parameter to "describe_options" is a "sprintf"-like string that is used in
generating the first line of the usage message. It's a one-line summary of how the
command is to be invoked. A typical usage description might be:
$usage_desc = "%c %o <source> <desc>";
%c will be replaced with what Getopt::Long::Descriptive thinks is the program name (it's
computed from $0, see "prog_name").
%o will be replaced with a list of the short options, as well as the text "[long
options...]" if any have been defined.
The rest of the usage description can be used to summarize what arguments are expected to
follow the program's options, and is entirely free-form.
Literal "%" characters will need to be written as "%%", just like with "sprintf".
@opt_spec
The @opt_spec part of the args to "describe_options" is used to configure option parsing
and to produce the usage message. Each entry in the list is an arrayref describing one
option, like this:
@opt_spec = (
[ "verbose|V" => "be noisy" ],
[ "logfile=s" => "file to log to" ],
);
The first value in the arrayref is a Getopt::Long-style option specification. In brief,
they work like this: each one is a pipe-delimited list of names, optionally followed by a
type declaration. Type declarations are '=x' or ':x', where "=" means a value is required
and ":" means it is optional. x may be 's' to indicate a string is required, 'i' for an
integer, or 'f' for a number with a fractional part. The type spec may end in "@" to
indicate that the option may appear multiple times.
For more information on how these work, see the Getopt::Long documentation.
The first name given should be the canonical name, as it will be used as the accessor
method on the $opt object. Dashes in the name will be converted to underscores, and all
letters will be lowercased. For this reason, all options should generally have a long-
form name.
The second value in the arrayref is a description of the option, for use in the usage
message.
Special Option Specifications
If the option specification (arrayref) is empty, it will have no effect other than causing
a blank line to appear in the usage message.
If the option specification contains only one element, it will be printed in the usage
message with no other effect.
If the option specification contains a third element, it adds extra constraints or
modifiers to the interpretation and validation of the value. These are the keys that may
be present in that hashref, and how they behave:
implies
implies => 'bar'
implies => [qw(foo bar)]
implies => { foo => 1, bar => 2 }
If option A has an "implies" entry, then if A is given, other options will be enabled.
The value may be a single option to set, an arrayref of options to set, or a hashref
of options to set to specific values.
required
required => 1
If an option is required, failure to provide the option will result in
"describe_options" printing the usage message and exiting.
hidden
hidden => 1
This option will not show up in the usage text.
You can achieve the same behavior by using the string "hidden" for the option's
description.
one_of
one_of => \@subopt_specs
This is useful for a group of options that are related. Each option spec is added to
the list for normal parsing and validation.
Your option name will end up with a value of the name of the option that was chosen.
For example, given the following spec:
[ "mode" => hidden => { one_of => [
[ "get|g" => "get the value" ],
[ "set|s" => "set the value" ],
[ "delete" => "delete it" ],
] } ],
No usage text for 'mode' will be displayed, but text for get, set, and delete will be
displayed.
If more than one of get, set, or delete is given, an error will be thrown.
So, given the @opt_spec above, and an @ARGV of "('--get')", the following would be
true:
$opt->get == 1;
$opt->mode eq 'get';
Note: "get" would not be set if "mode" defaulted to 'get' and no arguments were passed
in.
Even though the option sub-specs for "one_of" are meant to be 'first class' specs,
some options don't make sense with them, e.g. "required".
As a further shorthand, you may specify "one_of" options using this form:
[ mode => \@option_specs, \%constraints ]
Params::Validate
In addition, any constraint understood by Params::Validate may be used.
(Internally, all constraints are translated into Params::Validate options or
callbacks.)
%arg
The %arg to "describe_options" is optional. If the last parameter is a hashref, it
contains extra arguments to modify the way "describe_options" works. Valid arguments are:
getopt_conf - an arrayref of strings, passed to Getopt::Long::Configure
prog_name
This routine, exported on demand, returns the basename of $0, grabbed at compile-time.
You can override this guess by calling "prog_name($string)" yourself.
OTHER EXPORTS
"-types"
Any of the Params::Validate type constants ("SCALAR", etc.) can be imported as well. You
can get all of them at once by importing "-types".
"-all"
This import group will import "-type", "describe_options", and "prog_name".
CUSTOMIZING
Getopt::Long::Descriptive uses Sub::Exporter to build and export the "describe_options"
routine. By writing a new class that extends Getopt::Long::Descriptive, the behavior of
the constructed "describe_options" routine can be changed.
The following methods can be overridden:
usage_class
my $class = Getopt::Long::Descriptive->usage_class;
This returns the class to be used for constructing a Usage object, and defaults to
Getopt::Long::Descriptive::Usage.
SEE ALSO
o Getopt::Long
o Params::Validate
AUTHORS
o Hans Dieter Pearcey <hdp AT cpan.org>
o Ricardo Signes <rjbs AT cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2005 by Hans Dieter Pearcey.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.
perl v5.16.3 2012-11-01 Getopt::Long::Descriptive(3)
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Under GNU General Public License
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