NAME OptArgs - integrated argument and option processing VERSION 0.1.2 development release. SYNOPSIS #!/usr/bin/env perl use OptArgs; opt quiet => ( isa => 'Bool', alias => 'q', comment => 'output nothing while working', ); arg item => ( isa => 'Str', required => 1, comment => 'the item to paint', ); my $ref = optargs; print "Painting $ref->{item}\n" unless $ref->{quiet}; DESCRIPTION OptArgs processes Perl script *options* and *arguments*. This is in contrast with most modules in the Getopt::* namespace, which deal with options only. This module is duplicated as Getopt::Args, to cover both its original name and yet still be found in the mess that is Getopt::*. The following model is assumed by OptArgs for command-line applications: Command The program name - i.e. the filename be executed by the shell. Options Options are parameters that affect the way a command runs. They are generally not required to be present, but that is configurable. All options have a long form prefixed by '--', and may have a single letter alias prefixed by '-'. Arguments Arguments are positional parameters that that a command needs know in order to do its work. Confusingly, arguments can be optional. Sub-commands From a users point of view a sub-command is simply one or more arguments given to a Command that result in a particular action. However from a code perspective they are implemented as separate, stand-alone programs which are called by a dispatcher when the appropriate arguments are given. Simple Scripts To demonstrate lets put the code from the synopsis in a file called "paint" and observe the following interactions from the shell: $ ./paint usage: paint ITEM arguments: ITEM the item to paint options: --quiet, -q output nothing while working The "optargs()" function parses the commands arguments according to the "opt" and "arg" declarations and returns a single HASH reference. If the command is not called correctly then an exception is thrown with an automatically generated usage message as shown above. Because OptArgs knows about arguments it can detect errors relating to them: $ ./paint house red error: unexpected option or argument: red So let's add that missing argument definition: arg colour => ( isa => 'Str', default => 'blue', comment => 'the colour to use', ); And then check the usage again: $ ./paint usage: paint ITEM [COLOUR] arguments: ITEM the item to paint COLOUR the colour to use options: --quiet, -q output nothing while working It can be seen that the non-required argument "colour" appears inside square brackets indicating its optional nature. Let's add another argument with a positive value for the "greedy" parameter: arg message => ( isa => 'Str', comment => 'the message to paint on the item', greedy => 1, ); And check the new usage output: usage: paint ITEM [COLOUR] [MESSAGE...] arguments: ITEM the item to paint COLOUR the colour to use MESSAGE the message to paint on the item options: --quiet, -q output nothing while working Three dots (...) are postfixed to usage message for greedy arguments. By being greedy, the "message" argument will swallow whatever is left on the comand line: $ ./paint house blue Perl is great Painting in blue on house: "Perl is great". Note that it doesn't make sense to define any more arguments once you have a greedy argument. The order in which options and arguments (and sub-commands - see below) are defined is the order in which they appear in usage messsages, and is also the order in which the command line is parsed for them. Sub-Command Scripts Sub-commands are useful when your script performs different actions based on the value of a particular argument. To use sub-commands you build your application with the following structure: Command Class The Command Class defines the options and arguments for your *entire* application. The module is written the same way as a simple script but additionally specifies an argument of type 'SubCmd': package My::Cmd; use OptArgs; arg command => ( isa => 'SubCmd', comment => 'sub command to run', ); opt help => ( isa => 'Bool', comment => 'print a help message and exit', ishelp => 1, ); opt dry_run => ( isa => 'Bool', comment => 'do nothing', ); The "subcmd" function call is then used to define sub-command names and descriptions, and separate each sub-commands arguments and options: subcmd( cmd => 'start', comment => 'start a machine' ); arg machine => ( isa => 'Str', comment => 'the machine to start', ); opt quickly => ( isa => 'Bool', comment => 'start the machine quickly', ); subcmd( cmd => 'stop', comment => 'start the machine' ); arg machine => ( isa => 'Str', comment => 'the machine to stop', ); opt plug => ( isa => 'Bool', comment => 'stop the machine by pulling the plug', ); One nice thing about OptArgs is that options are *inherited*. You only need to specify something like a "dry-run" option once at the top level, and all sub-commands will see it if it has been set. Additionally, and this is the main reason why I wrote OptArgs, you do not have to load a whole bunch of slow-to-start modules ( I'm looking at you, Moose) just to get a help message. Sub-Command Classes These classes do the actual work. The entry point is a normal function, typically called something like "run", which is passed a single HASHref containing the option and argument values for the command. package My::Cmd::start; sub run { my $opts = shift; print "Starting $opts->{machine}\n"; } The function name can be whatever you like but it must be the same for every sub command. package My::Cmd::stop; sub run { my $opts = shift; print "Stoping $opts->{machine}\n"; } Command Script The command script is what the user runs, and does nothing more than dispatch to your Command Class, and eventually a Sub-Command Class. #!/usr/bin/perl use OptArgs qw/dispatch/; dispatch(qw/ run Your::Cmd /); One advantage to having a separate Command Class (and not defining everything inside a Command script) is that it is easy to run tests against your various Sub-Command Classes as follows: use Test::More; use Test::Output; use OptArgs qw/dispatch/; stdout_is( sub { dispatch( qw/ run My::Cmd start A / ) }, "Starting A\n", 'start' ); done_testing(); It is much easier to catch and measure exceptions when the code is running inside your test script, instead of having to fork and parse stderr strings. FUNCTIONS The following functions are exported (by default except for "dispatch") using Exporter::Tidy. opt( $name, %parameters ) Define a Command Option. If $name contains underscores then aliases with the underscores replaced by dashes (-) will be created. The following parameters are accepted: isa Required. Is mapped to a Getopt::Long type according to the following table: optargs Getopt::Long ------------------------------ 'Bool' '!' 'Counter' '+' 'Str' '=s' 'Int' '=i' 'Num' '=f' 'ArrayRef' 's@' 'HashRef' 's%' comment Required. Used to generate the usage/help message. default The value set when the option is not used. If this is a subroutine reference it will be called with a hashref containg all option/argument values after parsing the source has finished. The value to be set must be returned, and any changes to the hashref are ignored. alias A single character alias. ishelp When true flags this option as a help option, which when given on the command line results in a usage message exception. This flag is basically a cleaner way of doing the following in each (sub) command: my $opts = optargs; if ( $opts->{help} ) { die usage('help requested'); } hidden When true this option will not appear in usage messages unless the usage message is a help request. This is handy if you have developer-only options, or options that are very rarely used that you don't want cluttering up your normal usage message. arg( $name, %parameters ) Define a Command Argument with the following parameters: isa Required. Is mapped to a Getopt::Long type according to the following table: optargs Getopt::Long ------------------------------ 'Str' '=s' 'Int' '=i' 'Num' '=f' 'ArrayRef' 's@' 'HashRef' 's%' 'SubCmd' '=s' comment Required. Used to generate the usage/help message. required Set to a true value when the caller must specify this argument. Can not be used if a 'default' is given. default The value set when the argument is not given. Can not be used if 'required' is set. If this is a subroutine reference it will be called with a hashref containg all option/argument values after parsing the source has finished. The value to be set must be returned, and any changes to the hashref are ignored. greedy If true the argument swallows the rest of the command line. It doesn't make sense to define any more arguments once you have used this as they will never be seen. fallback A hashref containing an argument definition for the event that a sub-command match is not found. This parameter is only valid when "isa" is a "SubCmd". The hashref must contain "isa", "name" and "comment" key/value pairs, and may contain a "greedy" key/value pair. The Command Class "run" function will be called with the fallback argument integrated into the first argument like a regular sub-command. This is generally useful when you want to calculate a command alias from a configuration file at runtime, or otherwise run commands which don't easily fall into the OptArgs sub-command model. optargs( [ @argv ] ) -> HashRef Parse @ARGV by default (or @argv when given) and returns a hashref containing key/value pairs for options and arguments *combined*. An error / usage exception is thrown if an invalid combination of options and arguments is given. Note that @ARGV will be decoded into UTF-8 (if necessary) from whatever I18N::Langinfo says your current locale codeset is. usage( [$message] ) -> Str Returns a usage string prefixed with $message if given. subcmd( %parameters ) Create a sub-command. After this function is called further calls to "opt" and "arg" define options and arguments respectively for the sub-command. The following parameters are accepted: cmd Required. Either a scalar or an ARRAY reference containing the sub command name. comment Required. Used to generate the usage/help message. hidden When true this sub command will not appear in usage messages unless the usage message is a help request. This is handy if you have developer-only or rarely-used commands that you don't want cluttering up your normal usage message. dispatch( $function, $rootclass, [ @argv ] ) Parse @ARGV (or @argv if given) and dispatch to $function in the appropriate package name constructed from $rootclass. As an aid for testing, if the passed in argument @argv (not @ARGV) contains a HASH reference, the key/value combinations of the hash will be added as options. An undefined value means a boolean option. OPTIONAL BEHAVIOUR Certain OptArgs behaviour and/or output can be changed by setting the following package-level variables: $OptArgs::ABBREV If $OptArgs::ABBREV is a true value then sub-commands can be abbreviated, up to their shortest, unique values. $OptArgs::COLOUR If $OptArgs::COLOUR is a true value and "STDOUT" is connected to a terminal then usage and error messages will be colourized using terminal escape codes. $OptArgs::SORT If $OptArgs::SORT is a true value then sub-commands will be listed in usage messages alphabetically instead of in the order they were defined. SEE ALSO Getopt::Long, Exporter::Tidy SUPPORT & DEVELOPMENT This distribution is managed via github: https://github.com/mlawren/p5-OptArgs/tree/devel This distribution follows the semantic versioning model: http://semver.org/ Code is tidied up on Git commit using githook-perltidy: http://github.com/mlawren/githook-perltidy AUTHOR Mark Lawrence LICENSE Copyright 2012-2013 Mark Lawrence This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.