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 containing "::", since
exporting would be a problem.
LIBRARY USAGE
You can import the "type helpers" of a library by "use"ing 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.