NAME
OptArgs - integrated argument and option processing
VERSION
0.1.21 (2022-09-29)
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
*Deprecated*: development on OptArgs stopped in 2016. Consider using
OptArgs2 instead, which is faster and better looking in many ways
:-)
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 (an "OptArgs::Usage" object) 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 usual entry point would be
a method or a function, typically called something like "run",
which takes a HASHref argument:
package My::Cmd::start;
sub run {
my $self = shift;
my $opts = shift;
print "Starting $opts->{machine}\n";
}
package My::Cmd::stop;
sub run {
my $self = shift;
my $opts = shift;
print "Stoping $opts->{machine}\n";
}
Command Script
The command script is what the user runs, and does nothing more
than dispatch to your Command Class, and eventually a
Sub-Command Class.
#!/usr/bin/perl
use OptArgs qw/class_optargs/;
my ($class, $opts) = class_optargs('My::Cmd');
# Run object based sub-command classes
$class->new->run($opts);
# Or function based sub-command classes
$class->can('run')->($opts);
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/class_optargs/;
stdout_is(
sub {
my ($class,$opts) = class_optargs('My::Cmd','start','A');
$class->new->run($opts);
},
"Starting A\n", 'start'
);
eval { class_optargs('My::Cmd', '--invalid-option') };
isa_ok $@, 'OptArgs::Usage';
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.
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.
class_optargs( $rootclass, [ @argv ] ) -> ($class, $opts)
This is a more general version of the "optargs" function
described in detail below. It parses @ARGV (or @argv if given)
according to the options and arguments as defined in $rootclass,
and returns two values:
$class
The class name of the matching sub-command.
$opts
The matching argument and options for the sub-command.
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.
dispatch( $function, $rootclass, [ @argv ] )
[ NOTE: This function is badly designed and is depreciated. It
will be removed at some point before version 1.0.0]
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.
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%'
isa_name
When $OptArgs::PRINT_ISA is set to a true value, this value
will be printed instead of the generic value from "isa".
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.
For "Bool" options setting "default" to a true has a special
effect: the the usage message formats it as "--no-option"
instead of "--option". If you do use a true default value
for Bool options you probably want to reverse the normal
meaning of your "comment" value as well.
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
When $OptArgs::PRINT_OPT_ARG is set to a true value, this
value will be printed instead of the generic value from
"isa".
optargs( [ @argv ] ) -> HashRef
Parse @ARGV by default (or @argv when given) for the arguments
and options defined in the *current package*, and returns a
hashref containing key/value pairs for options and arguments
*combined*. An error / usage exception object ("OptArgs::Usage")
is thrown if an invalid combination of options and arguments is
given.
Note that @ARGV will be decoded into UTF-8 (if necessary) from
whatever I18N::Langinfo says your current locale codeset is.
subcmd( %parameters )
Create a sub-command. After this function is called further
calls to "opt" and "arg" define options and arguments
respectively for the sub-command. The following parameters are
accepted:
cmd Required. Either a scalar or an ARRAY reference containing
the sub command name.
comment
Required. Used to generate the usage/help message.
hidden
When true this sub command will not appear in usage messages
unless the usage message is a help request.
This is handy if you have developer-only or rarely-used
commands that you don't want cluttering up your normal usage
message.
usage( [$message] ) -> Str
Returns a usage string prefixed with $message if given.
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.
$OptArgs::PRINT_DEFAULT
If $OptArgs::PRINT_DEFAULT is a true value then usage will print
the default value of all options.
$OptArgs::PRINT_ISA
If $OptArgs::PRINT_ISA is a true value then usage will print the
type of argument a options expects.
SEE ALSO
OptArgs2, 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 <nomad@null.net>
LICENSE
Copyright 2012-2022 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.