NAME
    MooseX::Types - Organise your Moose types in libraries

SYNOPSIS
  Library Definition
      package MyLibrary;

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

      # 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 };

      # 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;

      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.

    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' };

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.

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 constrains, 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 typeconstraint and
        parameterize it with @args.

  create_base_type_constraint ($name)
        Given a String $name, find the matching typeconstraint.

  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 gotcha's 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' will have it's 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
        author's of this package realize that all the Moose documention 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.

SEE ALSO
        Moose, Moose::Util::TypeConstraints, MooseX::Types::Moose,
        Sub::Exporter

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

        Additional features by John Napiorkowski (jnapiorkowski)
        <jjnapiork@cpan.org>.

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