oracular (3) Type::Tiny::Manual::UsingWithMoose.3pm.gz
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.