NAME¶

MooseX::Types - Organise your Moose types in libraries

VERSION¶

version 0.50

SYNOPSIS¶

  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;

  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¶

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.

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¶

CAVEATS¶

The following are lists of gotchas and their workarounds for developers coming from the standard string based type constraint names

  subtype StrOrArrayRef => as Str | ArrayRef;

  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);

  - use Sub::Exporter -setup => { exports => [ qw(something) ] };
  + use Sub::Exporter -setup => { exports => [ qw(something MyStr) ] };

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.