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package Moose::Meta::TypeConstraint::Parameterizable;
use strict;
use warnings;
use metaclass;
our $VERSION = '1.09';
$VERSION = eval $VERSION;
our $AUTHORITY = 'cpan:STEVAN';
use base 'Moose::Meta::TypeConstraint';
use Moose::Meta::TypeConstraint::Parameterized;
use Moose::Util::TypeConstraints ();
__PACKAGE__->meta->add_attribute('constraint_generator' => (
accessor => 'constraint_generator',
predicate => 'has_constraint_generator',
));
sub generate_constraint_for {
my ($self, $type) = @_;
return unless $self->has_constraint_generator;
return $self->constraint_generator->($type->type_parameter)
if $type->is_subtype_of($self->name);
return $self->_can_coerce_constraint_from($type)
if $self->has_coercion
&& $self->coercion->has_coercion_for_type($type->parent->name);
return;
}
sub _can_coerce_constraint_from {
my ($self, $type) = @_;
my $coercion = $self->coercion;
my $constraint = $self->constraint_generator->($type->type_parameter);
return sub {
local $_ = $coercion->coerce($_);
$constraint->(@_);
};
}
sub _parse_type_parameter {
my ($self, $type_parameter) = @_;
return Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($type_parameter);
}
sub parameterize {
my ($self, $type_parameter) = @_;
my $contained_tc = $self->_parse_type_parameter($type_parameter);
## The type parameter should be a subtype of the parent's type parameter
## if there is one.
if(my $parent = $self->parent) {
if($parent->can('type_parameter')) {
unless ( $contained_tc->is_a_type_of($parent->type_parameter) ) {
require Moose;
Moose->throw_error("$type_parameter is not a subtype of ".$parent->type_parameter);
}
}
}
if ( $contained_tc->isa('Moose::Meta::TypeConstraint') ) {
my $tc_name = $self->name . '[' . $contained_tc->name . ']';
return Moose::Meta::TypeConstraint::Parameterized->new(
name => $tc_name,
parent => $self,
type_parameter => $contained_tc,
);
}
else {
require Moose;
Moose->throw_error("The type parameter must be a Moose meta type");
}
}
1;
__END__
=pod
=head1 NAME
Moose::Meta::TypeConstraint::Parameterizable - Type constraints which can take a parameter (ArrayRef)
=head1 DESCRIPTION
This class represents a parameterizable type constraint. This is a
type constraint like C<ArrayRef> or C<HashRef>, that can be
parameterized and made more specific by specifying a contained
type. For example, instead of just an C<ArrayRef> of anything, you can
specify that is an C<ArrayRef[Int]>.
A parameterizable constraint should not be used as an attribute type
constraint. Instead, when parameterized it creates a
L<Moose::Meta::TypeConstraint::Parameterized> which should be used.
=head1 INHERITANCE
C<Moose::Meta::TypeConstraint::Parameterizable> is a subclass of
L<Moose::Meta::TypeConstraint>.
=head1 METHODS
This class is intentionally not documented because the API is
confusing and needs some work.
=head1 BUGS
See L<Moose/BUGS> for details on reporting bugs.
=head1 AUTHOR
Stevan Little E<lt>stevan@iinteractive.comE<gt>
=head1 COPYRIGHT AND LICENSE
Copyright 2006-2010 by Infinity Interactive, Inc.
L<http://www.iinteractive.com>
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=cut
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