Provided by: libmoosex-types-perl_0.50-2_all 
NAME
MooseX::Types - Organise your Moose types in libraries
VERSION
version 0.50
SYNOPSIS
Library Definition
package MyLibrary;
# predeclare our own types
use MooseX::Types -declare => [
qw(
PositiveInt
NegativeInt
ArrayRefOfPositiveInt
ArrayRefOfAtLeastThreeNegativeInts
LotsOfInnerConstraints
StrOrArrayRef
MyDateTime
)
];
# import builtin types
use MooseX::Types::Moose qw/Int HashRef/;
# type definition.
subtype PositiveInt,
as Int,
where { $_ > 0 },
message { "Int is not larger than 0" };
subtype NegativeInt,
as Int,
where { $_ < 0 },
message { "Int is not smaller than 0" };
# type coercion
coerce PositiveInt,
from Int,
via { 1 };
# with parameterized constraints.
subtype ArrayRefOfPositiveInt,
as ArrayRef[PositiveInt];
subtype ArrayRefOfAtLeastThreeNegativeInts,
as ArrayRef[NegativeInt],
where { scalar(@$_) > 2 };
subtype LotsOfInnerConstraints,
as ArrayRef[ArrayRef[HashRef[Int]]];
# with TypeConstraint Unions
subtype StrOrArrayRef,
as Str|ArrayRef;
# class types
class_type 'DateTime';
# or better
class_type MyDateTime, { class => 'DateTime' };
coerce MyDateTime,
from HashRef,
via { DateTime->new(%$_) };
1;
Usage
package Foo;
use Moose;
use MyLibrary qw( PositiveInt NegativeInt );
# use the exported constants as type names
has 'bar',
isa => PositiveInt,
is => 'rw';
has 'baz',
isa => NegativeInt,
is => 'rw';
sub quux {
my ($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 type system provided by Moose effectively makes all of its builtin type global, as are
any types you declare with Moose. This means that every module that declares a type named
"PositiveInt" is sharing the same type object. This can be a problem when different parts
of the code base want to use the same name for different things.
This package lets you declare types using short names, but behind the scenes it namespaces
all your type declarations, effectively prevent name clashes between packages.
This is done by creating a type library module like "MyApp::Types" and then importing
types from that module into other modules.
As a side effect, the declaration mechanism allows you to write type names as barewords
(really function calls), which catches typos in names at compile time rather than run
time.
This module also provides some helper functions for using Moose types outside of attribute
declarations.
If you mix string-based names with types created by this module, it will warn, with a few
exceptions. If you are declaring a "class_type()" or "role_type()" within your type
library, or if you use a fully qualified name like "MyApp::Foo".
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.
You also don't need to use "warnings" and "strict", since the definition of a library
automatically exports those.
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.
The exporting mechanism is, since version 0.5, implemented via a wrapper around
Sub::Exporter. This means you can do something like this:
use MyLibrary TypeA => { -as => 'MyTypeA' },
TypeB => { -as => 'MyTypeB' };
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 has not defined any coercions will
lead to a compile-time error.
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 MRO::Compat;
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.
$undef_message
A message that will be thrown when type functionality is used but the type does not
yet exist.
RECURSIVE SUBTYPES
As of version 0.08, Moose::Types has experimental support for Recursive subtypes. This
will allow:
subtype Tree() => as HashRef[Str|Tree];
Which validates things like:
{key=>'value'};
{key=>{subkey1=>'value', subkey2=>'value'}}
And so on. This feature is new and there may be lurking bugs so don't be afraid to hunt
me down with patches and test cases if you have trouble.
NOTES REGARDING TYPE UNIONS
MooseX::Types uses MooseX::Types::TypeDecorator to do some overloading which generally
allows you to easily create union types:
subtype StrOrArrayRef,
as Str|ArrayRef;
As with parameterized constraints, this overloading extends to modules using the types you
define in a type library.
use Moose;
use MooseX::Types::Moose qw(HashRef Int);
has 'attr' => ( isa => HashRef | Int );
And everything should just work as you'd think.
METHODS
import
Installs the MooseX::Types::Base class into the caller and exports types according to the
specification described in "LIBRARY DEFINITION". This will continue to
Moose::Util::TypeConstraints' "import" method to export helper functions you will need to
declare your types.
type_export_generator
Generate a type export, e.g. "Int()". This will return either a
Moose::Meta::TypeConstraint object, or alternatively a MooseX::Types::UndefinedType object
if the type was not yet defined.
create_arged_type_constraint ($name, @args)
Given a String $name with @args find the matching type constraint and parameterize it with
@args.
create_base_type_constraint ($name)
Given a String $name, find the matching type constraint.
create_type_decorator ($type_constraint)
Given a $type_constraint, return a lightweight MooseX::Types::TypeDecorator instance.
coercion_export_generator
This generates a coercion handler function, e.g. "to_Int($value)".
check_export_generator
Generates a constraint check closure, e.g. "is_Int($value)".
CAVEATS
The following are lists of gotchas and their workarounds for developers coming from the
standard string based type constraint names
Uniqueness
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.
Argument separation ('=>' versus ',')
The perlop manpage has this to say about the '=>' operator: "The => operator is a synonym
for the comma, but forces any word (consisting entirely of word characters) to its left to
be interpreted as a string (as of 5.001). This includes words that might otherwise be
considered a constant or function call."
Due to this stringification, the following will NOT work as you might think:
subtype StrOrArrayRef => as Str | ArrayRef;
The "StrOrArrayRef" type will have its stringification activated -- this causes the
subtype to not be created. Since the bareword type constraints are not strings you really
should not try to treat them that way. You will have to use the ',' operator instead.
The authors of this package realize that all the Moose documentation and examples nearly
uniformly use the '=>' version of the comma operator and this could be an issue if you are
converting code.
Patches welcome for discussion.
Compatibility with Sub::Exporter
If you want to use Sub::Exporter with a Type Library, you need to make sure you export all
the type constraints declared AS WELL AS any additional export targets. For example if you
do:
package TypeAndSubExporter;
use MooseX::Types::Moose qw(Str);
use MooseX::Types -declare => [qw(MyStr)];
use Sub::Exporter -setup => { exports => [qw(something)] };
subtype MyStr, as Str;
sub something {
return 1;
}
# then in another module ...
package Foo;
use TypeAndSubExporter qw(MyStr);
You'll get a ""MyStr" is not exported by the TypeAndSubExporter module" error. It can be
worked around by:
- use Sub::Exporter -setup => { exports => [ qw(something) ] };
+ use Sub::Exporter -setup => { exports => [ qw(something MyStr) ] };
This is a workaround and I am exploring how to make these modules work better together. I
realize this workaround will lead a lot of duplication in your export declarations and
will be onerous for large type libraries. Patches and detailed test cases welcome. See
the tests directory for a start on this.
COMBINING TYPE LIBRARIES
You may want to combine a set of types for your application with other type libraries,
like MooseX::Types::Moose or MooseX::Types::Common::String.
The MooseX::Types::Combine module provides a simple API for combining a set of type
libraries together.
SEE ALSO
Moose, Moose::Util::TypeConstraints, MooseX::Types::Moose, Sub::Exporter
ACKNOWLEDGEMENTS
Many thanks to the "#moose" cabal on "irc.perl.org".
SUPPORT
Bugs may be submitted through the RT bug tracker
<https://rt.cpan.org/Public/Dist/Display.html?Name=MooseX-Types> (or
bug-MooseX-Types@rt.cpan.org <mailto:bug-MooseX-Types@rt.cpan.org>).
There is also a mailing list available for users of this distribution, at
<http://lists.perl.org/list/moose.html>.
There is also an irc channel available for users of this distribution, at "#moose" on
"irc.perl.org" <irc://irc.perl.org/#moose>.
AUTHOR
Robert "phaylon" Sedlacek <rs@474.at>
CONTRIBUTORS
• Karen Etheridge <ether@cpan.org>
• Dave Rolsky <autarch@urth.org>
• John Napiorkowski <jjnapiork@cpan.org>
• Robert 'phaylon' Sedlacek <phaylon@cpan.org>
• Rafael Kitover <rkitover@cpan.org>
• Florian Ragwitz <rafl@debian.org>
• Matt S Trout <mst@shadowcat.co.uk>
• Tomas Doran (t0m) <bobtfish@bobtfish.net>
• Jesse Luehrs <doy@tozt.net>
• Mark Fowler <mark@twoshortplanks.com>
• Hans Dieter Pearcey <hdp@weftsoar.net>
• Graham Knop <haarg@haarg.org>
• Paul Fenwick <pjf@perltraining.com.au>
• Kent Fredric <kentfredric@gmail.com>
• Justin Hunter <justin.d.hunter@gmail.com>
COPYRIGHT AND LICENCE
This software is copyright (c) 2007 by Robert "phaylon" Sedlacek.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.