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.IX Title "Type::Tiny::Manual::UsingWithClassTiny 3pm"
.TH Type::Tiny::Manual::UsingWithClassTiny 3pm "2023-07-21" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
Type::Tiny::Manual::UsingWithClassTiny \- use of Type::Tiny with Class::Tiny
.SH "MANUAL"
.IX Header "MANUAL"
Class::Tiny is an even-smaller-than-Moo class builder.
.PP
Let's translate the classic Horse class from Moo to Class::Tiny.
.PP
Moo:
.PP
.Vb 4
\&  package Horse {
\&    use Moo;
\&    use Types::Standard qw( Str Num ArrayRef );
\&    use namespace::autoclean;
\&    
\&    has name       => ( is => \*(Aqro\*(Aq, isa => Str, required => 1 );
\&    has gender     => ( is => \*(Aqro\*(Aq, isa => Str );
\&    has age        => ( is => \*(Aqrw\*(Aq, isa => Num );
\&    has children   => (
\&      is       => \*(Aqro\*(Aq,
\&      isa      => ArrayRef,
\&      default  => sub { return [] },
\&    );
\&  }
.Ve
.PP
Class::Tiny:
.PP
.Vb 8
\&  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 Object );
\&    use Type::Params qw( signature_for );
\&    use namespace::autoclean;
\&    
\&    # type checks
\&    signature_for BUILD => (
\&      method => Object,
\&      named  => [
\&        name       => Str,
\&        gender     => Optional[Str],
\&        age        => Optional[Num],
\&        children   => Optional[ArrayRef],
\&        ()         => Slurpy[Any],
\&      ],
\&      fallback => 1,
\&    );
\&    signature_for [ \*(Aqname\*(Aq, \*(Aqgender\*(Aq, \*(Aqchildren\*(Aq ] => (
\&      method     => Object,
\&      positional => [],
\&    );
\&    signature_for age => (
\&      method     => Object,
\&      positional => [ Optional[Num] ],
\&    );
\&  }
.Ve
.PP
What's going on here?
.PP
Well, Class::Tiny, after it has built a new object, will do this:
.PP
.Vb 1
\&  $self\->BUILD($args);
.Ve
.PP
(Technically, it calls \f(CW\*(C`BUILD\*(C'\fR 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.
.PP
We use \f(CW\*(C`signature_for\*(C'\fR from Type::Params to wrap the original \f(CW\*(C`BUILD\*(C'\fR
method (which doesn't exist, so \f(CW\*(C`fallback => 1\*(C'\fR will just assume an
empty sub) with a type check for its arguments. The type check is just a
\&\fBDict\fR that checks the class's required and optional attributes and includes
\&\fBSlurpy[Any]\fR at the end to be flexible for subclasses adding new
attributes.
.PP
Then we wrap the \f(CW\*(C`name\*(C'\fR, \f(CW\*(C`gender\*(C'\fR, and \f(CW\*(C`children\*(C'\fR methods with checks
to make sure they're only being called as getters, and we wrap \f(CW\*(C`age\*(C'\fR,
allowing it to be called as a setter with a \fBNum\fR.
.PP
There are also a couple of \s-1CPAN\s0 modules that can help you out.
.SS "Class::Tiny::ConstrainedAccessor"
.IX Subsection "Class::Tiny::ConstrainedAccessor"
Class::Tiny::ConstrainedAccessor creates a \f(CW\*(C`BUILD\*(C'\fR and accessors that
enforce Type::Tiny constraints.  Attribute types are passed to
Class::Tiny::ConstrainedAccessor; attribute defaults are passed to Class::Tiny.
.PP
.Vb 10
\&  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 [] },
\&    };
\&  }
.Ve
.SS "Class::Tiny::Antlers"
.IX Subsection "Class::Tiny::Antlers"
Class::Tiny::Antlers provides Moose-like syntax for Class::Tiny, including
support for \f(CW\*(C`isa\*(C'\fR.  You do not also need to use Class::Tiny itself.
.PP
.Vb 4
\&  package Horse {
\&    use Class::Tiny::Antlers qw(has);
\&    use Types::Standard qw( Str Num ArrayRef );
\&    use namespace::autoclean;
\&    
\&    has name       => (
\&      is        => \*(Aqro\*(Aq,
\&      isa       => Str,
\&      default   => sub { die "name is required" },
\&    );
\&    has gender     => ( is => \*(Aqro\*(Aq,    isa => Str );
\&    has age        => ( is => \*(Aqrw\*(Aq,    isa => Num );
\&    has children   => (
\&      is        => \*(Aqro\*(Aq,
\&      isa       => ArrayRef,
\&      default   => sub { return [] },
\&    );
\&  }
.Ve
.SH "NEXT STEPS"
.IX Header "NEXT STEPS"
Here's your next step:
.IP "\(bu" 4
Type::Tiny::Manual::UsingWithOther
.Sp
Using Type::Tiny with Class::InsideOut, Params::Check, and Object::Accessor.
.SH "AUTHOR"
.IX Header "AUTHOR"
Toby Inkster <tobyink@cpan.org>.
.SH "COPYRIGHT AND LICENCE"
.IX Header "COPYRIGHT AND LICENCE"
This software is copyright (c) 2013\-2014, 2017\-2023 by Toby Inkster.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
.SH "DISCLAIMER OF WARRANTIES"
.IX Header "DISCLAIMER OF WARRANTIES"
\&\s-1THIS PACKAGE IS PROVIDED \*(L"AS IS\*(R" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.\s0