Type::Tiny::Manual::UsingWithMouse - phpMan

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.