Type::Tiny::Manual::UsUseriContributed)Type::Tiny::Manual::UsingWithMoose(3pm)
NAME
Type::Tiny::Manual::UsingWithMoose - how to use Type::Tiny with Moose
MANUAL
First read Type::Tiny::Manual::Moo, Type::Tiny::Manual::Moo2, and
Type::Tiny::Manual::Moo3. Everything in those parts of the manual
should work exactly the same in Moose.
This part of the manual will focus on Moose-specifics.
Why Use Type::Tiny At All?
Moose does have a built-in type constraint system which is fairly
convenient to use, but there are several reasons you should consider
using Type::Tiny instead.
• Type::Tiny type constraints will usually be faster than Moose
built-ins. Even without Type::Tiny::XS installed, Type::Tiny
usually produces more efficient inline code than Moose. Coercions
will usually be a lot faster.
• Type::Tiny provides helpful methods like "where" and
"plus_coercions" that allow type constraints and coercions to be
easily tweaked on a per-attribute basis.
Something like this is much harder to do with plain Moose types:
has name => (
is => "ro",
isa => Str->plus_coercions(
ArrayRef[Str], sub { join " ", @$_ },
),
coerce => 1,
);
Moose tends to encourage defining coercions globally, so if you
wanted one Str attribute to be able to coerce from ArrayRef[Str],
then all Str attributes would coerce from ArrayRef[Str], and they'd
all do that coercion in the same way. (Even if it might make sense
to join by a space in some places, a comma in others, and a line
break in others!)
• Type::Tiny provides automatic deep coercions, so if type Xyz has a
coercion, the following should "just work":
has xyzlist => ( is => 'ro', isa => ArrayRef[Xyz], coerce => 1 );
• Type::Tiny offers a wider selection of built-in types.
• By using Type::Tiny, you can use the same type constraints and
coercions for attributes and method parameters, in Moose and non-
Moose code.
Type::Utils
If you've used Moose::Util::TypeConstraints, you may be accustomed to
using a DSL for declaring type constraints:
use Moose::Util::TypeConstraints;
subtype 'Natural',
as 'Int',
where { $_ > 0 };
There's a module called Type::Utils that provides a very similar DSL
for declaring types in Type::Library-based type libraries.
package My::Types {
use Type::Library -base;
use Type::Utils;
use Types::Standard qw( Int );
declare 'Natural',
as Int,
where { $_ > 0 };
}
Personally I prefer the more object-oriented way to declare types
though.
Since Type::Library 1.012, a shortcut has been available for importing
Type::Library and Type::Utils at the same time:
package MyType {
use Type::Library -base, -utils;
...;
}
In Moose you might also declare types like this within classes and
roles too. Unlike Moose, Type::Tiny doesn't keep types in a single
global flat namespace, so this doesn't work quite the same with
Type::Utils. It still creates the type, but it doesn't store it in any
type library; the type is returned.
package My::Class {
use Moose;
use Type::Utils;
use Types::Standard qw( Int );
my $Natural = # store type in a variable
declare 'Natural',
as Int,
where { $_ > 0 };
has number => ( is => 'ro', isa => $Natural );
}
But really, isn't the object-oriented way cleaner?
package My::Class {
use Moose;
use Types::Standard qw( Int );
has number => (
is => 'ro',
isa => Int->where('$_ > 0'),
);
}
Type::Tiny and MooseX::Types
Types::Standard should be a drop-in replacement for MooseX::Types. And
Types::Common::Numeric and Types::Common::String should easily replace
MooseX::Types::Common::Numeric and MooseX::Types::Common::String.
That said, if you do with to use a mixture of Type::Tiny and
MooseX::Types, they should fit together pretty seamlessly.
use Types::Standard qw( ArrayRef );
use MooseX::Types::Common::Numeric qw( PositiveInt );
# this should just work
my $list_of_nums = ArrayRef[PositiveInt];
# and this
my $list_or_num = ArrayRef | PositiveInt;
"-moose" Import Parameter
If you have read this far in the manual, you will know that this is the
usual way to import type constraints:
use Types::Standard qw( Int );
And the "Int" which is imported is a function that takes no arguments
and returns the Int type constraint, which is a blessed object in the
Type::Tiny class.
Type::Tiny mocks the Moose::Meta::TypeConstraint API so well that most
Moose and MooseX code will not be able to tell the difference.
But what if you need a real Moose::Meta::TypeConstraint object?
use Types::Standard -moose, qw( Int );
Now the "Int" function imported will return a genuine native Moose type
constraint.
This flag is mostly a throwback from when Type::Tiny native objects
didn't directly work in Moose. In 99.9% of cases, there is no reason to
use it and plenty of reasons not to. (Moose native type constraints
don't offer helpful methods like "plus_coercions" and "where".)
"moose_type" Method
Another quick way to get a native Moose type constraint object from a
Type::Tiny object is to call the "moose_type" method:
use Types::Standard qw( Int );
my $tiny_type = Int;
my $moose_type = $tiny_type->moose_type;
Internally, this is what the "-moose" flag makes imported functions do.
NEXT STEPS
Here's your next step:
• Type::Tiny::Manual::UsingWithMouse
How to use Type::Tiny with Mouse, including the advantages of
Type::Tiny over built-in type constraints, and Mouse-specific
features.
AUTHOR
Toby Inkster <tobyink@cpan.org>.
COPYRIGHT AND LICENCE
This software is copyright (c) 2013-2014, 2017-2023 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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