Type::Tiny::Manual::UsingWithMoo3 - phpMan

NAME
    Type::Tiny::Manual::UsingWithMoo3 - alternative use of Type::Tiny with
    Moo

MANUAL
  Type Registries
    In all the examples so far, we have imported a collection of type
    constraints into each class:

      package Horse {
        use Moo;
        use Types::Standard qw( Str ArrayRef HashRef Int Any InstanceOf );
        use Types::Common::Numeric qw( PositiveInt );
        use Types::Common::String qw( NonEmptyStr );

        has name    => ( is => 'ro', isa => Str );
        has father  => ( is => 'ro', isa => InstanceOf["Horse"] );
        ...;
      }

    This creates a bunch of subs in the Horse namespace, one for each type.
    We've used namespace::autoclean to clean these up later.

    But it is also possible to avoid pulling all these into the Horse
    namespace. Instead we'll use a type registry:

      package Horse {
        use Moo;
        use Type::Registry qw( t );

        t->add_types('-Standard');
        t->add_types('-Common::String');
        t->add_types('-Common::Numeric');

        t->alias_type('InstanceOf["Horse"]' => 'Horsey');

        has name     => ( is => 'ro', isa => t('Str') );
        has father   => ( is => 'ro', isa => t('Horsey') );
        has mother   => ( is => 'ro', isa => t('Horsey') );
        has children => ( is => 'ro', isa => t('ArrayRef[Horsey]') );
        ...;
      }

    You don't even need to import the "t()" function. Types::Registry can be
    used in an entirely object-oriented way.

      package Horse {
        use Moo;
        use Type::Registry;

        my $reg = Type::Registry->for_me;

        $reg->add_types('-Standard');
        $reg->add_types('-Common::String');
        $reg->add_types('-Common::Numeric');

        $reg->alias_type('InstanceOf["Horse"]' => 'Horsey');

        has name => ( is => 'ro', isa => $reg->lookup('Str') );
        ...;
      }

    You could create two registries with entirely different definitions for
    the same named type.

      my $dracula = Aristocrat->new(name => 'Dracula');

      package AristocracyTracker {
        use Type::Registry;

        my $reg1 = Type::Registry->new;
        $reg1->add_types('-Common::Numeric');
        $reg1->alias_type('PositiveInt' => 'Count');

        my $reg2 = Type::Registry->new;
        $reg2->add_types('-Standard');
        $reg2->alias_type('InstanceOf["Aristocrat"]' => 'Count');

        $reg1->lookup("Count")->assert_valid("1");
        $reg2->lookup("Count")->assert_valid($dracula);
      }

    Type::Registry uses "AUTOLOAD", so things like this work:

      $reg->ArrayRef->of( $reg->Int );

    Although you can create as many registries as you like, Type::Registry
    will create a default registry for each package.

      # Create a new empty registry.
      #
      my $reg = Type::Registry->new;

      # Get the default registry for my package.
      # It will be pre-populated with any types we imported using `use`.
      #
      my $reg = Type::Registry->for_me;

      # Get the default registry for some other package.
      #
      my $reg = Type::Registry->for_class("Horse");

    Type registries are a convenient place to store a bunch of types without
    polluting your namespace. They are not the same as type libraries
    though. Types::Standard, Types::Common::String, and
    Types::Common::Numeric are type libraries; packages that export types
    for others to use. We will look at how to make one of those later.

    For now, here's the best way to think of the difference:

    *   Type registry

        Curate a collection of types for me to use here in this class. This
        collection is an implementaion detail.

    *   Type library

        Export a collection of types to be used across multiple classes.
        This collection is part of your API.

  Importing Functions
    We've seen how, for instance, Types::Standard exports a sub called "Int"
    that returns the Int type object.

      use Types::Standard qw( Int );

      my $type = Int;
      $type->check($value) or die $type->get_message($value);

    Type libraries are also capable of exporting other convenience
    functions.

   "is_*"
    This is a shortcut for checking a value meets a type constraint:

      use Types::Standard qw( is_Int );

      if ( is_Int($value) ) {
        ...;
      }

    Calling "is_Int($value)" will often be marginally faster than calling
    "Int->check($value)" because it avoids a method call. (Method calls in
    Perl end up slower than normal function calls.)

    Using things like "is_ArrayRef" in your code might be preferable to
    "ref($value) eq "ARRAY"" because it's neater, leads to more consistent
    type checking, and might even be faster. (Type::Tiny can be pretty fast;
    it is sometimes able to export these functions as XS subs.)

    If checking type constraints like "is_ArrayRef" or "is_InstanceOf",
    there's no way to give a parameter. "is_ArrayRef[Int]($value)" doesn't
    work, and neither does "is_ArrayRef(Int, $value)" nor
    "is_ArrayRef($value, Int)". For some types like "is_InstanceOf", this
    makes them fairly useless; without being able to give a class name, it
    just acts the same as "is_Object". See "Exporting Parameterized Types"
    for a solution. Also, check out isa.

    There also exists a generic "is" function.

      use Types::Standard qw( ArrayRef Int );
      use Type::Utils qw( is );

      if ( is ArrayRef[Int], \@numbers ) {
        ...;
      }

   "assert_*"
    While "is_Int($value)" returns a boolean, "assert_Int($value)" will
    throw an error if the value does not meet the constraint, and return the
    value otherwise. So you can do:

      my $sum = assert_Int($x) + assert_Int($y);

    And you will get the sum of integers $x and $y, and an explosion if
    either of them is not an integer!

    Assert is useful for quick parameter checks if you are avoiding
    Type::Params for some strange reason:

      sub add_numbers {
        my $x = assert_Num(shift);
        my $y = assert_Num(shift);
        return $x + $y;
      }

    You can also use a generic "assert" function.

      use Type::Utils qw( assert );

      sub add_numbers {
        my $x = assert Num, shift;
        my $y = assert Num, shift;
        return $x + $y;
      }

   "to_*"
    This is a shortcut for coercion:

      my $truthy = to_Bool($value);

    It trusts that the coercion has worked okay. You can combine it with an
    assertion if you want to make sure.

      my $truthy = assert_Bool(to_Bool($value));

   Shortcuts for exporting functions
    This is a little verbose:

      use Types::Standard qw( Bool is_Bool assert_Bool to_Bool );

    Isn't this a little bit nicer?

      use Types::Standard qw( +Bool );

    The plus sign tells a type library to export not only the type itself,
    but all of the convenience functions too.

    You can also use:

      use Types::Standard -types;   # export Int, Bool, etc
      use Types::Standard -is;      # export is_Int, is_Bool, etc
      use Types::Standard -assert;  # export assert_Int, assert_Bool, etc
      use Types::Standard -to;      # export to_Bool, etc
      use Types::Standard -all;     # just export everything!!!

    So if you imagine the functions exported by Types::Standard are like
    this:

      qw(
        Str             is_Str          assert_Str
        Num             is_Num          assert_Num
        Int             is_Int          assert_Int
        Bool            is_Bool         assert_Bool     to_Bool
        ArrayRef        is_ArrayRef     assert_ArrayRef
      );
      # ... and more

    Then "+" exports a horizonal group of those, and "-" exports a vertical
    group.

  Exporting Parameterized Types
    It's possible to export parameterizable types like ArrayRef, but it is
    also possible to export *parameterized* types.

      use Types::Standard qw( ArrayRef Int );
      use Types::Standard (
        '+ArrayRef' => { of => Int, -as => 'IntList' },
      );

      has numbers => (is => 'ro', isa => IntList);

    Using "is_IntList($value)" should be significantly faster than
    "ArrayRef->of(Int)->check($value)".

    This trick only works for parameterized types that have a single
    parameter, like ArrayRef, HashRef, InstanceOf, etc. (Sorry, "Dict" and
    "Tuple"!)

  Do What I Mean!
      use Type::Utils qw( dwim_type );

      dwim_type("ArrayRef[Int]")

    "dwim_type" will look up a type constraint from a string and attempt to
    guess what you meant.

    If it's a type constraint that you seem to have imported with "use",
    then it should find it. Otherwise, if you're using Moose or Mouse, it'll
    try asking those. Or if it's in Types::Standard, it'll look there. And
    if it still has no idea, then it will assume dwim_type("Foo") means
    dwim_type("InstanceOf['Foo']").

    It just does a big old bunch of guessing.

    The "is" function will use "dwim_type" if you pass it a string as a
    type.

      use Type::Utils qw( is );

      if ( is "ArrayRef[Int]", \@numbers ) {
        ...;
      }

NEXT STEPS
    You now know pretty much everything there is to know about how to use
    type libraries.

    Here's your next step:

    *   Type::Tiny::Manual::Libraries

        Defining your own type libraries, including extending existing
        libraries, defining new types, adding coercions, defining
        parameterizable types, and the declarative style.

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.