/ 
MooseX-Types-0.02
River stage four • 371 direct dependents • 1742 total dependents
/ MooseX::Types

NAME

MooseX::Types - Organise your Moose types in libraries

SYNOPSIS

Library Definition

package MyLibrary;
use strict;

# predeclare our own types
use MooseX::Types 
    -declare => [qw( PositiveInt NegativeInt )];

# import builtin types
use MooseX::Types::Moose 'Int';

# type definition
subtype PositiveInt, 
    as Int, 
    where { $_ > 0 },
    message { "Int is not larger than 0" };

subtype NegativeInt,
    as Int,
    where { $_ < 0 },
    message { "Int is not smaller than 0" };

# type coercion
coerce PositiveInt,
    from Int,
        via { 1 };

1;

Usage

package Foo;
use Moose;
use MyLibrary qw( PositiveInt NegativeInt );

# use the exported constants as type names
has 'bar',
    isa    => PositiveInt,
    is     => 'rw';
has 'baz',
    isa    => NegativeInt,
    is     => 'rw';

sub quux {
    my ($self, $value);

    # test the value
    print "positive\n" if is_PositiveInt($value);
    print "negative\n" if is_NegativeInt($value);

    # coerce the value, NegativeInt doesn't have a coercion
    # helper, since it didn't define any coercions.
    $value = to_PositiveInt($value) or die "Cannot coerce";
}

1;

DESCRIPTION

The types provided with Moose are by design global. This package helps you to organise and selectively import your own and the built-in types in libraries. As a nice side effect, it catches typos at compile-time too.

However, the main reason for this module is to provide an easy way to not have conflicts with your type names, since the internal fully qualified names of the types will be prefixed with the library's name.

This module will also provide you with some helper functions to make it easier to use Moose types in your code.

TYPE HANDLER FUNCTIONS

$type

A constant with the name of your type. It contains the type's fully qualified name. Takes no value, as all constants.

is_$type

This handler takes a value and tests if it is a valid value for this $type. It will return true or false.

to_$type

A handler that will take a value and coerce it into the $type. It will return a false value if the type could not be coerced.

Important Note: This handler will only be exported for types that can do type coercion. This has the advantage that a coercion to a type that cannot hasn't defined any coercions will lead to a compile-time error.

LIBRARY DEFINITION

A MooseX::Types is just a normal Perl module. Unlike Moose itself, it does not install use strict and use warnings in your class by default, so this is up to you.

The only thing a library is required to do is

use MooseX::Types -declare => \@types;

with @types being a list of types you wish to define in this library. This line will install a proper base class in your package as well as the full set of handlers for your declared types. It will then hand control over to Moose::Util::TypeConstraints' import method to export the functions you will need to declare your types.

If you want to use Moose' built-in types (e.g. for subtyping) you will want to

use MooseX::Types::Moose @types;

to import the helpers from the shipped MooseX::Types::Moose library which can export all types that come with Moose.

You will have to define coercions for your types or your library won't export a "to_$type" coercion helper for it.

Note that you currently cannot define types containint ::, since exporting would be a problem.

LIBRARY USAGE

You can import the "type helpers" of a library by useing it with a list of types to import as arguments. If you want all of them, use the :all tag. For example:

use MyLibrary      ':all';
use MyOtherLibrary qw( TypeA TypeB );

MooseX::Types comes with a library of Moose' built-in types called MooseX::Types::Moose.

WRAPPING A LIBRARY

You can define your own wrapper subclasses to manipulate the behaviour of a set of library exports. Here is an example:

package MyWrapper;
use strict;
use Class::C3;
use base 'MooseX::Types::Wrapper';

sub coercion_export_generator {
    my $class = shift;
    my $code = $class->next::method(@_);
    return sub {
        my $value = $code->(@_);
        warn "Coercion returned undef!"
            unless defined $value;
        return $value;
    };
}

1;

This class wraps the coercion generator (e.g., to_Int()) and warns if a coercion returned an undefined value. You can wrap any library with this:

package Foo;
use strict;
use MyWrapper MyLibrary => [qw( Foo Bar )],
              Moose     => [qw( Str Int )];

...
1;

The Moose library name is a special shortcut for MooseX::Types::Moose.

Generator methods you can overload

type_export_generator( $short, $full )

Creates a closure returning the type's Moose::Meta::TypeConstraint object.

check_export_generator( $short, $full, $undef_message )

This creates the closure used to test if a value is valid for this type.

coercion_export_generator( $short, $full, $undef_message )

This is the closure that's doing coercions.

Provided Parameters

$short

The short, exported name of the type.

$full

The fully qualified name of this type as Moose knows it.

$undef_message

A message that will be thrown when type functionality is used but the type does not yet exist.

METHODS

import

Installs the MooseX::Types::Base class into the caller and exports types according to the specification described in "LIBRARY DEFINITION". This will continue to Moose::Util::TypeConstraints' import method to export helper functions you will need to declare your types.

type_export_generator

Generate a type export, e.g. Int(). This will return either a Moose::Meta::TypeConstraint object, or alternatively a MooseX::Types::UndefinedType object if the type was not yet defined.

coercion_export_generator

This generates a coercion handler function, e.g. to_Int($value).

check_export_generator

Generates a constraint check closure, e.g. is_Int($value).

CAVEATS

A library makes the types quasi-unique by prefixing their names with (by default) the library package name. If you're only using the type handler functions provided by MooseX::Types, you shouldn't ever have to use a type's actual full name.

SEE ALSO

Moose, Moose::Util::TypeConstraints, MooseX::Types::Moose

AUTHOR AND COPYRIGHT

Robert 'phaylon' Sedlacek <rs@474.at>, with many thanks to the #moose cabal on irc.perl.org.

LICENSE

This program is free software; you can redistribute it and/or modify it under the same terms as perl itself.