Class::InsideOut¶

You want Class::InsideOut 1.13 or above, which has support for blessed and overloaded objects (including Type::Tiny type constraints) for the "get_hook" and "set_hook" options.

  package Person {
    use Class::InsideOut qw( public );
    use Types::Standard qw( Str Int );
    use Types::Common::Numeric qw( PositiveInt );
    use Type::Params qw( signature );
    
    # Type checks are really easy.
    # Just supply the type as a set hook.
    public name => my %_name, {
      set_hook => Str,
    };
    
    # Define a type that silently coerces negative values
    # to positive. It's silly, but it works as an example!
    my $Years = PositiveInt->plus_coercions(Int, q{ abs($_) });
    
    # Coercions are more annoying, but possible.
    public age => my %_age, {
      set_hook => sub { $_ = $Years->assert_coerce($_) },
    };
    
    # Parameter checking for methods is as expected.
    sub get_older {
      state $check = signature( method => 1, positional => [ $Years ] );
      my ( $self, $years ) = $check->( @_ );
      $self->_set_age( $self->age + $years );
    }
  }

Params::Check and Object::Accessor¶

The Params::Check allow() function, the "allow" option for the Params::Check check() function, and the input validation mechanism for Object::Accessor all work in the same way, which is basically a limited pure-Perl implementation of the smart match operator. While this doesn't directly support Type::Tiny constraints, it does support coderefs. You can use Type::Tiny's "compiled_check" method to obtain a suitable coderef.

Param::Check example:

  my $tmpl = {
    name => { allow => Str->compiled_check },
    age  => { allow => Int->compiled_check },
  };
  check($tmpl, { name => "Bob", age => 32 })
    or die Params::Check::last_error();

Object::Accessor example:

  my $obj = Object::Accessor->new;
  $obj->mk_accessors(
    { name => Str->compiled_check },
    { age  => Int->compiled_check },
  );

Caveat: Object::Accessor doesn't die when a value fails to meet its type constraint; instead it outputs a warning to STDERR. This behaviour can be changed by setting "$Object::Accessor::FATAL = 1".

Class::Struct¶

This is proof-of-concept of how Type::Tiny can be used to constrain attributes for Class::Struct. It's probably not a good idea to use this in production as it slows down "UNIVERSAL::isa" globally.

  use Types::Standard -types;
  use Class::Struct;
  {
    my %MAP;
    my $orig_isa = \&UNIVERSAL::isa;
    *UNIVERSAL::isa = sub {
      return $MAP{$1}->check($_[0])
        if $_[1] =~ /^CLASSSTRUCT::TYPETINY::(.+)$/ && exists $MAP{$1};
      goto $orig;
    };
    my $orig_dn = \&Type::Tiny::display_name;
    *Type::Tiny::display_name = sub {
      if (caller(1) eq 'Class::Struct') {
        $MAP{$_[0]{uniq}} = $_[0];
        return "CLASSSTRUCT::TYPETINY::".$_[0]{uniq};
      }
      goto $orig_dn;
    };
  }
  struct Person => [ name => Str, age => Int ];
  my $bob = Person->new(
    name => "Bob",
    age  => 21,
  );
  $bob->name("Robert");   # okay
  $bob->name([]);         # dies

Class::Plain¶

There is not currently a high level of integration, but here's a quick example of type checking attributes in the constructor.

If any of your accessors are ":rw" then you would also need to add type checks to those.

  use Class::Plain;
  
  class Point {
    use Types::Common -types, -sigs;
    
    field x :reader;
    field y :reader;
    
    signature_for new => (
      method => !!1,
      bless  => !!0,
      named  => [
        x => Int,
        y => Int,
      ],
    );
    
    method as_arrayref () {
      return [ $self->x, $self->y ];
    }
  }

The following signature may also be of interest:

  signature_for new => (
    method   => !!1,
    multiple => [
      {
        named => [
          x => Int,
          y => Int,
        ],
        bless => !!0,
      },
      {
        positional => [ Int, Int ],
        goto_next  => sub {
          my ( $class, $x, $y ) = @_;
          return ( $class, { x => $x, y => $y } ),
        },
      },
    ],
  );

This would allow your class to be instantiated using any of the following:

  my $point11 = Point->new( { x => 1, y => 1 } );
  my $point22 = Point->new(   x => 2, y => 2   );
  my $point33 = Point->new( 3, 3 );