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Type::Tiny::Manual::UsUseriContribuType::Tiny::Manual::UsingWithClassTiny(3pm)

NAME
       Type::Tiny::Manual::UsingWithClassTiny - use of Type::Tiny with
       Class::Tiny

MANUAL
       Class::Tiny is an even-smaller-than-Moo class builder.

       Let's translate the classic Horse class from Moo to Class::Tiny.

       Moo:

         package Horse {
           use Moo;
           use Types::Standard qw( Str Num ArrayRef );
           use namespace::autoclean;

           has name       => ( is => 'ro', isa => Str, required => 1 );
           has gender     => ( is => 'ro', isa => Str );
           has age        => ( is => 'rw', isa => Num );
           has children   => (
             is       => 'ro',
             isa      => ArrayRef,
             default  => sub { return [] },
           );
         }

       Class::Tiny:

         package Horse {
           use Class::Tiny qw( gender age ), {
             name     => sub { die "name is required"; },
             children => sub { return [] },
           };
           use Types::Standard qw( Str Num ArrayRef Dict Optional slurpy Any);
           use Type::Params qw( wrap_methods compile );
           use namespace::autoclean;

           # type checks
           wrap_methods(
             BUILD    => [Dict[
               name       => Str,
               gender     => Optional[Str],
               age        => Optional[Num],
               children   => Optional[ArrayRef],
               slurpy Any,
             ]],
             name     => [],
             gender   => [],
             age      => Optional[Num],
             children => [],
           );
         }

       What's going on here?

       Well, Class::Tiny, after it has built a new object, will do this:

         $self->BUILD($args);

       (Technically, it calls "BUILD" not just for the current class, but for
       all parent classes too.) We can hook onto this in order to check type
       constraints for the constructor.

       We use "wrap_methods" from Type::Params to wrap the original "BUILD"
       method (which doesn't exist, so "wrap_methods" will just assume an
       empty sub) with a type check for $args. The type check is just a Dict
       that checks the class's required and optional attributes and includes
       slurpy Any at the end to be flexible for subclasses adding new
       attributes.

       Then we wrap the "name", "gender", and "children" methods with checks
       to make sure they're only being called as getters, and we wrap "age",
       allowing it to be called as a setter with a Num.

       There are also a couple of CPAN modules that can help you out.

   Class::Tiny::ConstrainedAccessor
       Class::Tiny::ConstrainedAccessor creates a "BUILD" and accessors that
       enforce Type::Tiny constraints.  Attribute types are passed to
       Class::Tiny::ConstrainedAccessor; attribute defaults are passed to
       Class::Tiny.

         package Horse {
           use Types::Standard qw( Str Num ArrayRef );
           use Class::Tiny::ConstrainedAccessor {
             name     => Str,
             gender   => Str,
             age      => Num,
             children => ArrayRef,
           };
           use Class::Tiny qw( gender age ), {
             name     => sub { die "name is required"; },
             children => sub { return [] },
           };
         }

   Class::Tiny::Antlers
       Class::Tiny::Antlers provides Moose-like syntax for Class::Tiny,
       including support for "isa".  You do not also need to use Class::Tiny
       itself.

         package Horse {
           use Class::Tiny::Antlers qw(has);
           use Types::Standard qw( Str Num ArrayRef );
           use namespace::autoclean;

           has name       => (
             is        => 'ro',
             isa       => Str,
             default   => sub { die "name is required" },
           );
           has gender     => ( is => 'ro',    isa => Str );
           has age        => ( is => 'rw',    isa => Num );
           has children   => (
             is        => 'ro',
             isa       => ArrayRef,
             default   => sub { return [] },
           );
         }

NEXT STEPS
       Here's your next step:

       o   Type::Tiny::Manual::UsingWithOther

           Using Type::Tiny with Class::InsideOut, Params::Check, and
           Object::Accessor.

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.

perl v5.32.1                      2Type::Tiny::Manual::UsingWithClassTiny(3pm)