1 package Moose::Meta::TypeConstraint::Parameterizable;
7 our $AUTHORITY = 'cpan:STEVAN';
9 use base 'Moose::Meta::TypeConstraint';
10 use Moose::Meta::TypeConstraint::Parameterized;
11 use Moose::Util::TypeConstraints ();
13 __PACKAGE__->meta->add_attribute('constraint_generator' => (
14 accessor => 'constraint_generator',
15 predicate => 'has_constraint_generator',
18 sub generate_constraint_for {
19 my ($self, $type) = @_;
21 return unless $self->has_constraint_generator;
23 return $self->constraint_generator->($type->type_parameter)
24 if $type->is_subtype_of($self->name);
26 return $self->_can_coerce_constraint_from($type)
27 if $self->has_coercion
28 && $self->coercion->has_coercion_for_type($type->parent->name);
33 sub _can_coerce_constraint_from {
34 my ($self, $type) = @_;
35 my $coercion = $self->coercion;
36 my $constraint = $self->constraint_generator->($type->type_parameter);
38 local $_ = $coercion->coerce($_);
43 sub _parse_type_parameter {
44 my ($self, $type_parameter) = @_;
45 return Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($type_parameter);
49 my ($self, $type_parameter) = @_;
51 my $contained_tc = $self->_parse_type_parameter($type_parameter);
53 ## The type parameter should be a subtype of the parent's type parameter
56 if(my $parent = $self->parent) {
57 if($parent->can('type_parameter')) {
58 unless ( $contained_tc->is_a_type_of($parent->type_parameter) ) {
60 Moose->throw_error("$type_parameter is not a subtype of ".$parent->type_parameter);
65 if ( $contained_tc->isa('Moose::Meta::TypeConstraint') ) {
66 my $tc_name = $self->name . '[' . $contained_tc->name . ']';
67 return Moose::Meta::TypeConstraint::Parameterized->new(
70 type_parameter => $contained_tc,
75 Moose->throw_error("The type parameter must be a Moose meta type");
82 # ABSTRACT: Type constraints which can take a parameter (ArrayRef)
91 This class represents a parameterizable type constraint. This is a
92 type constraint like C<ArrayRef> or C<HashRef>, that can be
93 parameterized and made more specific by specifying a contained
94 type. For example, instead of just an C<ArrayRef> of anything, you can
95 specify that is an C<ArrayRef[Int]>.
97 A parameterizable constraint should not be used as an attribute type
98 constraint. Instead, when parameterized it creates a
99 L<Moose::Meta::TypeConstraint::Parameterized> which should be used.
103 C<Moose::Meta::TypeConstraint::Parameterizable> is a subclass of
104 L<Moose::Meta::TypeConstraint>.
108 This class is intentionally not documented because the API is
109 confusing and needs some work.
113 See L<Moose/BUGS> for details on reporting bugs.