Getopt::Long::DescriptUser3Contributed Perl DocumeGetopt::Long::Descriptive(3)NAMEGetopt::Long::Descriptive - Getopt::Long, but simpler and more powerful
VERSION
version 0.090
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 $opt->verbose;
...and running "my-program --help" will produce:
my-program [-psv] [long options...] <some-arg>
-s --server the server to connect to
-p --port the port to connect to
-v --verbose print extra stuff
--help print usage message and exit
DESCRIPTIONGetopt::Long::Descriptive is yet another Getopt library. It's built
atop Getopt::Long, and gets a lot of its features, but tries to avoid
making you think about its huge array of options.
It also provides usage (help) messages, data validation, and a few
other useful features.
FUNCTIONSGetopt::Long::Descriptive only exports one routine by default:
"describe_options". All GLD's exports are exported by Sub::Exporter.
describe_options
my ($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".
CUSTOMIZINGGetopt::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
· Getopt::Long
· Params::Validate
AUTHORS
· Hans Dieter Pearcey <hdp@cpan.org>
· Ricardo Signes <rjbs@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 v5.14.2 2011-04-22 Getopt::Long::Descriptive(3)
