OptArgs2 - command-line argument and option processor
2.0.0_4 (2022-09-28)
#!/usr/bin/env perl use OptArgs2; # For simple scripts use optargs() my $args = optargs( comment => 'script to paint things', optargs => [ item => { isa => 'Str', required => 1, comment => 'the item to paint', }, quiet => { isa => '--Flag', alias => 'q', comment => 'output nothing while working', }, ], ); print "Painting $args->{item}\n" unless $args->{quiet}; # For complex multi-command applications # use cmd(), subcmd() and class_optargs() cmd 'My::app' => ( comment => 'handy work app', optargs => [ command => { isa => 'Str', required => 1, comment => 'the action to take', }, quiet => { isa => '--Flag', alias => 'q', comment => 'output nothing while working', }, ], ); subcmd 'My::app::prepare' => ( comment => 'prepare something', optargs => [ item => { isa => 'Str', required => 1, comment => 'the item to prepare', }, ], ); subcmd 'My::app::paint' => ( comment => 'paint something', optargs => [ item => { isa => 'Str', required => 1, comment => 'the item to paint', }, color => { isa => '--Str', alias => 'c', comment => 'your faviourite', default => 'blue', }, ], ); my ( $class, $opts, $file ) = class_optargs('My::app'); require $file; $class->new($opts);
OptArgs2 processes command line arguments, options, and subcommands according to the following definitions:
A program run from the command line to perform a task.
Arguments are positional parameters that pass information to a command. Arguments can be optional, but they should not be confused with Options below.
Options are non-positional parameters that pass information to a command. They are generally not required to be present (hence the name Option) but that is configurable. All options have a long form prefixed by '--', and may have a single letter alias prefixed by '-'.
From the users point of view a subcommand is a special argument with its own set of arguments and options. However from a code authoring perspective subcommands are often implemented as stand-alone programs, called from the main script when the appropriate command arguments are given.
OptArgs2 version 2.0.0 was a large re-write to improve the API and code. Users upgrading from version 0.0.11 or OptArgs need to be aware of the following:
Commands and subcommands are now explicitly defined using optargs(), cmd() and subcmd(). The arguments to optargs() have changed to match cmd().
optargs()
cmd()
subcmd()
Optargs definitions must now be defined in an array reference containing key/value pairs as shown in the synopsis. Fallback arguments have been replaced with a new fallthru option.
fallthru
Users must specifically require the class if they want to use it afterwards.
A Bool option without a default is now displayed with the "[no-]" prefix. What this means in practise is that many of your existing Bool options most likely would become Flag options instead.
To demonstrate the simple use case (i.e. with no subcommands) lets put the code from the synopsis in a file called paint and observe the following interactions from the shell:
paint
$ ./paint usage: paint ITEM [OPTIONS...] arguments: ITEM the item to paint *required* options: --help, -h print a usage message and exit --quiet, -q output nothing while working
The optargs() function parses the command line (@ARGV) according to the included declarations and returns a single HASH reference. If the command is not called correctly then an exception is thrown containing an automatically generated usage message as shown above. Because OptArgs2 fully knows the valid arguments and options it can detect a wide range of errors:
@ARGV
$ ./paint wall Perl is great error: unexpected option or argument: Perl
So let's add that missing argument definition inside the optargs ref
optargs => [ ... message => { isa => 'Str', comment => 'the message to paint on the item', greedy => 1, }, ],
And then check the usage again:
$ ./paint usage: paint ITEM [MESSAGE...] [OPTIONS...] arguments: ITEM the item to paint, *required* MESSAGE the message to paint on the item options: --help, -h print a usage message and exit --quiet, -q output nothing while working
Note that optional arguments are surrounded by square brackets, and that three dots (...) are postfixed to greedy arguments. A greedy argument will swallow whatever is left on the comand line:
$ ./paint wall Perl is great Painting on wall: "Perl is great".
Note that it probably doesn't make sense to define any more arguments once you have a greedy argument. Let's imagine you now want the user to be able to choose the colour if they don't like the default. An option might make sense here, specified by a leading '--' type:
optargs => [ ... colour => { isa => '--Str', default => 'blue', comment => 'the colour to use', }, ],
This now produces the following usage output:
usage: paint ITEM [MESSAGE...] [OPTIONS...] arguments: ITEM the item to paint MESSAGE the message to paint on the item options: --colour=STR, -c the colour to use [blue] --help, -h print a usage message and exit --quiet, -q output nothing while working
Commands with subcommands require a different coding model and syntax which we will describe over three phases:
Your command structure is defined using calls to the cmd() and subcmd() functions. The first argument to both functions is the name of the Perl class that implements the (sub-)command.
cmd 'App::demo' => ( comment => 'the demo command', optargs => [ command => { isa => 'SubCmd', required => 1, comment => 'command to run', }, quiet => { isa => '--Flag', alias => 'q', comment => 'run quietly', }, ], ); subcmd 'App::demo::foo' => ( comment => 'demo foo', optargs => [ action => { isa => 'Str', required => 1, comment => 'command to run', }, ], ); subcmd 'App::demo::bar' => ( comment => 'demo bar', optargs => [ baz => { isa => '--Counter', comment => '+1', }, ], ); # Command hierarchy for the above code, # printed by using '-h' twice: # # demo COMMAND [OPTIONS...] # demo foo ACTION [OPTIONS...] # demo bar [OPTIONS...]
An argument of type 'SubCmd' is an explicit indication that subcommands can occur in that position. The command hierarchy is based upon the natural parent/child structure of the class names. This definition can be done in your main script, or in one or more separate packages or plugins, as you like.
The class_optargs() function is called to parse the @ARGV array and call the appropriate arg() and opt() definitions as needed. It's first argument is generally the top-level command name you used in your first cmd() call.
class_optargs()
arg()
opt()
my ($class, $opts) = class_optargs('App::demo'); printf "Running %s with %s\n", $class, Dumper($opts) unless $opts->{quiet};
The additional return value $class is the name of the actual (sub-)command to which the $opts HASHref applies. Usage exceptions are raised just the same as with the optargs() function.
$class
$opts
error: unknown option "--invalid" usage: demo COMMAND [OPTIONS...] COMMAND command to run bar demo bar foo demo foo --quiet, -q run quietly
Note that options are inherited by subcommands.
Once you have the subcommand name and the option/argument hashref you can either execute the action or dispatch to the appropriate class/package as you like.
There are probably several ways to layout command classes when you have lots of subcommands. Here is one way that seems to work for this module's author.
I typically put the actual (sub-)command implementations in lib/App/demo.pm and lib/App/demo/subcmd.pm. App::demo itself only needs to exists if the root command does something. However I tend to also make App::demo the base class for all subcommands so it is often a non-trivial piece of code.
App::demo::OptArgs is where I put all of my command definitions with names that match the actual implementation modules.
package App::demo::OptArgs; use OptArgs2; cmd 'App::demo' => { comment => 'the demo app', optargs => [ # arg => 'Type, ... # opt => '--Type, ... ], }
The reason for keeping this separate from lib/App/demo.pm is speed of loading. I don't want to have to load all of the modules that App::demo itself uses just to find out that I called the command incorrectly.
The command script itself is then usually fairly short:
#!/usr/bin/env perl use OptArgs2 'class_optargs'; use App::demo::OptArgs; my ($class, $opts, $file) = class_optargs('App::demo'); require $file; $class->new($opts)->run;
Arguments are key/hashref pairs defined inside a cmd() or subcmd() optargs arrayref like so:
optargs => [ name => { isa => 'Str', comment => 'the file to parse', default => '-', greedy => 0, # required => 0 | 1, # fallthru => 0 | 1, }, ],
The following paramters are accepted:
Required. Used to generate the usage/help message.
The value set when the argument is not given. Conflicts with the 'required' parameter.
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.
If true the argument swallows the rest of the command line.
Only relevant for SubCmd types. Normally, a "required" SubCmd will raise an error when the given argument doesn't match any subcommand. However, when fallthru is true the non-subcommand-matching argument will be passed back to the class_optargs() caller.
This is typically useful when you have aliases that you can expand into real subcommands.
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'
When provided this parameter will be presented instead of the generic presentation for the 'isa' parameter.
Set to a true value when the caller must specify this argument. Conflicts with the 'default' parameter.
Boolean to indicate if the default value should be shown in usage messages. Overrides the (sub-)command's show_default setting.
show_default
Arguments are defined similar to arguments inside a cmd() or subcmd() optargs arrayref like so:
optargs => [ colour => { isa => '--Str', alias => 'c', comment => 'the colour to paint', default => 'blue', show_default => 1, }, ],
Any underscores in the name (i.e. the optargs key) are replaced by dashes (-) for presentation and command-line parsing. The following paramters are accepted:
A single character alias.
The value set when the option is not given. Conflicts with the 'required' parameter.
If this is a subroutine reference it will be called with a hashref containing 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.
Set to a true value when the caller must specify this option. Conflicts with the 'default' parameter.
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.
isa Getopt::Long --- ------------ '--ArrayRef' 's@' '--Flag' '!' '--Bool' '!' '--Counter' '+' '--HashRef' 's%' '--Int' '=i' '--Num' '=f' '--Str' '=s'
The trigger parameter lets you define a subroutine that is called after processing before usage exceptions are raised. This is primarily to support --help or --version options which would typically override usage errors.
opt version => ( isa => 'Flag', alias => 'V', comment => 'print version string and exit', trigger => sub { my ( $cmd, $value ) = @_; die "$cmd version $VERSION\n"; } );
The trigger subref is passed two parameters: a OptArgs2::Cmd object and the value (if any) of the option. The OptArgs2::Cmd object is an internal one.
Usage messages attempt to present as much information as possible to the caller. Here is a brief overview of how the various types look and/or change depending on things like defaults.
The presentation of Bool options in usage messages is as follows:
Name Type Default Presentation ---- ---- ------- ------------ option Bool undef --[no-]option option Bool true --no-option option Bool false --option option Counter * --option
The Flag option type is like a Bool that can only be set to true or left undefined. This makes sense for things such as --help or --version for which you never need to see a "--no" prefix.
--help
--version
Name Type Default Presentation ---- ---- ------- ------------ option Flag always undef --option
Note that Flags also makes sense for "negative" options which will only ever turn things off:
Name Type Default Presentation ---- ---- ------- ------------ no_option Flag always undef --no-option # In Perl no_foo => { isa => '--Flag', comment => 'disable the foo feature', } # Then later do { } unless $opts->{no_foo}
The remaining types are presented as follows:
Name Type isa_name Presentation ---- ---- -------- ------------ option ArrayRef - --option Str option HashRef - --option Str option Int - --option Int option Num - --option Num option Str - --option Str option * XX --option XX
Defaults TO BE COMPLETED.
The following functions are exported by default.
Parse @ARGV by default (or @argv when given) for the arguments and options defined for command $class. @ARGV will first be decoded into UTF-8 (if necessary) from whatever I18N::Langinfo says your current locale codeset is.
Returns the following values:
The actual subcommand name that was matched by parsing the arguments. This may be the same as $class.
a hashref containing combined key/value pairs for options and arguments.
A file fragment (matching $subclass) suitable for passing to require.
$subclass
require
Throws an error / usage exception object (typically OptArgs2::Usage) for missing or invalid arguments/options. Uses OptArgs2::Pager for Help output.
OptArgs2::Usage
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.
@argv
Returns the terminal column width.
Define a top-level command identified by $class which is typically a Perl package name. The following parameters are accepted:
When set to true then subcommands can be abbreviated, up to their shortest, unique values.
A description of the command. Required.
A subref containing argument and option definitions. Note that options are inherited by subcommands so you don't need to define them again in child subcommands.
By default cmd() automatically adds a default '--help' option. When used once a standard help message is displayed. When used twice a help tree showing subcommands is displayed. To disable the automatic help set no_help to a true value.
no_help
Boolean indicating if usage messages should use ANSI terminal color codes to highlight different elements. True by default.
Boolean indicating if default values for options and arguments should be shown in usage messages. Can be overriden by sub-commands, args and opts. Off by default.
This is a convenience function for single-level commands that:
passes it's arguments directly to cmd(),
calls class_optargs() to parse '@ARGV' and returns the $opts HASHref result directly.
Returns the terminal row height.
Defines the subcommand $subclass of a previously defined (sub-)command.
Accepts the same parameters as cmd() in addition to the following:
Hide the existence of this subcommand in non-help usage messages. This is handy if you have developer-only or rarely-used commands that you don't want cluttering up your normal usage message.
Only exported on request, this function returns the usage string for the command $class.
OptArgs2::Pager, OptArgs2::StatusLine, Getopt::Long
This module used to duplicate itself on CPAN as Getopt::Args2, but as of the version 2 series that is no longer the case.
This distribution is managed via github:
https://github.com/mlawren/p5-OptArgs2/
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
Mark Lawrence <nomad@null.net>
Copyright 2016-2022 Mark Lawrence <nomad@null.net>
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.
To install OptArgs2, copy and paste the appropriate command in to your terminal.
cpanm
cpanm OptArgs2
CPAN shell
perl -MCPAN -e shell install OptArgs2
For more information on module installation, please visit the detailed CPAN module installation guide.