phpman > perldoc > Type::Tiny::Manual::UsingWithMouse(3pm)

NAME
    Type::Tiny::Manual::UsingWithMouse - how to use Type::Tiny with Mouse

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 Mouse.

    This part of the manual will focus on Mouse-specifics.

    Overall, Type::Tiny is less well-tested with Mouse than it is with Moose and Moo, but there are
    still a good number of test cases for using Type::Tiny with Mouse, and there are no known major
    issues with Type::Tiny's Mouse support.

  Why Use Type::Tiny At All?
    Mouse 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 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 Mouse types:

          has name => (
            is      => "ro",
            isa     => Str->plus_coercions(
              ArrayRef[Str], sub { join " ", @$_ },
            ),
            coerce  => 1,
          );

        Mouse 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":

          isa 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 Mouse and non-Mouse code.

  Type::Utils
    If you've used Mouse::Util::TypeConstraints, you may be accustomed to using a DSL for declaring
    type constraints:

      use Mouse::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.

    In Mouse you might also declare types like this within classes and roles too. Unlike Mouse,
    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 Mouse;
        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 Mouse;
        use Types::Standard qw( Int );

        has number => (
          is   => 'ro',
          isa  => Int->where('$_ > 0'),
        );
      }

  Type::Tiny and MouseX::Types
    Types::Standard should be a drop-in replacement for MooseX::Types. And Types::Common::Numeric
    and Types::Common::String should easily replace MouseX::Types::Common::Numeric and
    MouseX::Types::Common::String.

    That said, if you do with to use a mixture of Type::Tiny and MouseX::Types, they should fit
    together pretty seamlessly.

      use Types::Standard qw( ArrayRef );
      use MouseX::Types::Mouse qw( Int );

      # this should just work
      my $list_of_nums = ArrayRef[Int];

      # and this
      my $list_or_num = ArrayRef | Int;

  "-mouse" 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 Mouse::Meta::TypeConstraint API so well that most Mouse and MouseX code
    will not be able to tell the difference.

    But what if you need a real Mouse::Meta::TypeConstraint object?

      use Types::Standard -mouse, qw( Int );

    Now the "Int" function imported will return a genuine native Mouse type constraint.

    This flag is mostly a throwback from when Type::Tiny native objects *didn't* directly work in
    Mouse. In 99.9% of cases, there is no reason to use it and plenty of reasons not to. (Mouse
    native type constraints don't offer helpful methods like "plus_coercions" and "where".)

  "mouse_type" Method
    Another quick way to get a native Mouse type constraint object from a Type::Tiny object is to
    call the "mouse_type" method:

      use Types::Standard qw( Int );

      my $tiny_type   = Int;
      my $mouse_type  = $tiny_type->mouse_type;

    Internally, this is what the "-mouse" flag makes imported functions do.

  Type::Tiny Performance
    Type::Tiny should run pretty much as fast as Mouse types do. This is because, when possible, it
    will use Mouse's XS implementations of type checks to do the heavy lifting.

    There are a few type constraints where Type::Tiny prefers to do things without Mouse's help
    though, for consistency and correctness. For example, the Mouse XS implementation of Bool is...
    strange... it accepts blessed objects that overload "bool", but only if they return false. If
    they return true, it's a type constraint error.

    Using Type::Tiny instead of Mouse's type constraints shouldn't make a significant difference to
    the performance of your code.

NEXT STEPS
    Here's your next step:

    *   Type::Tiny::Manual::UsingWithClassTiny

        Including how to Type::Tiny in your object's "BUILD" method, and third-party shims between
        Type::Tiny and Class::Tiny.

AUTHOR
    Toby Inkster <tobyink AT cpan.org>.

COPYRIGHT AND LICENCE
    This software is copyright (c) 2013-2014, 2017-2021 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.