MooseX::Types(3) User Contributed Perl Documentation MooseX::Types(3)NAME
MooseX::Types - Organise your Moose types in libraries
VERSION
version 0.35
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.
$undef_message
A message that will be thrown when type functionality is used but
the type does not yet exist.
RECURSIVE SUBTYPES
As of version 0.08, Moose::Types has experimental support for Recursive
subtypes. This will allow:
subtype Tree() => as HashRef[Str|Tree];
Which validates things like:
{key=>'value'};
{key=>{subkey1=>'value', subkey2=>'value'}}
And so on. This feature is new and there may be lurking bugs so don't
be afraid to hunt me down with patches and test cases if you have
trouble.
NOTES REGARDING TYPE UNIONS
MooseX::Types uses MooseX::Types::TypeDecorator to do some overloading
which generally allows you to easily create union types:
subtype StrOrArrayRef,
as Str|ArrayRef;
As with parameterized constrains, this overloading extends to modules
using the types you define in a type library.
use Moose;
use MooseX::Types::Moose qw(HashRef Int);
has 'attr' => ( isa => HashRef | Int );
And everything should just work as you'd think.
METHODS
import
Installs the MooseX::Types::Base class into the caller and exports
types according to the specification described in "LIBRARY DEFINITION".
This will continue to Moose::Util::TypeConstraints' "import" method to
export helper functions you will need to declare your types.
type_export_generator
Generate a type export, e.g. "Int()". This will return either a
Moose::Meta::TypeConstraint object, or alternatively a
MooseX::Types::UndefinedType object if the type was not yet defined.
create_arged_type_constraint ($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 $name, find the matching type constraint.
create_type_decorator ($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' 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 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.
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. Upi can workaround 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".
CONTRIBUTORS
jnapiorkowski: John Napiorkowski <jjnapiork@cpan.org>
caelum: Rafael Kitover <rkitover@cpan.org>
rafl: Florian Ragwitz <rafl@debian.org>
hdp: Hans Dieter Pearcey <hdp@cpan.org>
autarch: Dave Rolsky <autarch@urth.org>
AUTHOR
Robert "phaylon" Sedlacek <rs@474.at>
COPYRIGHT AND LICENSE
This software is copyright (c) 2012 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.
perl v5.16.2 2012-05-18 MooseX::Types(3)
