package Mouse::Meta::Attribute; use strict; use warnings; use Carp (); use Mouse::Util qw(:meta); use Mouse::Meta::TypeConstraint; use Mouse::Meta::Method::Accessor; sub _process_options{ my($class, $name, $args) = @_; # taken from Class::MOP::Attribute::new defined($name) or $class->throw_error('You must provide a name for the attribute'); if(!exists $args->{init_arg}){ $args->{init_arg} = $name; } # 'required' requires eigher 'init_arg', 'builder', or 'default' my $can_be_required = defined( $args->{init_arg} ); if(exists $args->{builder}){ $class->throw_error('builder must be a defined scalar value which is a method name') if ref $args->{builder} || !(defined $args->{builder}); $can_be_required++; } elsif(exists $args->{default}){ if(ref $args->{default} && ref($args->{default}) ne 'CODE'){ $class->throw_error("References are not allowed as default values, you must " . "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"); } $can_be_required++; } if( $args->{required} && !$can_be_required ) { $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg"); } # taken from Mouse::Meta::Attribute->new and _process_args-> if(exists $args->{is}){ my $is = $args->{is}; if($is eq 'ro'){ $args->{reader} ||= $name; } elsif($is eq 'rw'){ if(exists $args->{writer}){ $args->{reader} ||= $name; } else{ $args->{accessor} ||= $name; } } elsif($is eq 'bare'){ # do nothing, but don't complain (later) about missing methods } else{ $is = 'undef' if !defined $is; $class->throw_error("I do not understand this option (is => $is) on attribute ($name)"); } } my $tc; if(exists $args->{isa}){ $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_isa_type_constraint($args->{isa}); } elsif(exists $args->{does}){ # TODO # $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_does_type_constraint($args->{does}); } $tc = $args->{type_constraint}; if($args->{coerce}){ defined($tc) || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)"); $args->{weak_ref} && $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)"); } if ($args->{lazy_build}) { exists($args->{default}) && $class->throw_error("You can not use lazy_build and default for the same attribute ($name)"); $args->{lazy} = 1; $args->{builder} ||= "_build_${name}"; if ($name =~ /^_/) { $args->{clearer} ||= "_clear${name}"; $args->{predicate} ||= "_has${name}"; } else { $args->{clearer} ||= "clear_${name}"; $args->{predicate} ||= "has_${name}"; } } if ($args->{auto_deref}) { defined($tc) || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)"); ( $tc->is_a_type_of('ArrayRef') || $tc->is_a_type_of('HashRef') ) || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)"); } if (exists $args->{trigger}) { ('CODE' eq ref $args->{trigger}) || $class->throw_error("Trigger must be a CODE ref on attribute ($name)"); } if ($args->{lazy}) { (exists $args->{default} || defined $args->{builder}) || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it"); } # XXX: for backward compatibility (with method modifiers) if($class->can('canonicalize_args') != \&canonicalize_args){ %{$args} = $class->canonicalize_args($name, %{$args}); } return; } sub new { my $class = shift; my $name = shift; my %args = (@_ == 1) ? %{ $_[0] } : @_; $class->_process_options($name, \%args); $args{name} = $name; my $instance = bless \%args, $class; # extra attributes if($class ne __PACKAGE__){ $class->meta->_initialize_instance($instance,\%args); } # XXX: there is no fast way to check attribute validity # my @bad = ...; # if(@bad){ # @bad = sort @bad; # Carp::cluck("Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad"); # } return $instance } # readers sub name { $_[0]->{name} } sub associated_class { $_[0]->{associated_class} } sub accessor { $_[0]->{accessor} } sub reader { $_[0]->{reader} } sub writer { $_[0]->{writer} } sub predicate { $_[0]->{predicate} } sub clearer { $_[0]->{clearer} } sub handles { $_[0]->{handles} } sub _is_metadata { $_[0]->{is} } sub is_required { $_[0]->{required} } sub default { $_[0]->{default} } sub is_lazy { $_[0]->{lazy} } sub is_lazy_build { $_[0]->{lazy_build} } sub is_weak_ref { $_[0]->{weak_ref} } sub init_arg { $_[0]->{init_arg} } sub type_constraint { $_[0]->{type_constraint} } sub trigger { $_[0]->{trigger} } sub builder { $_[0]->{builder} } sub should_auto_deref { $_[0]->{auto_deref} } sub should_coerce { $_[0]->{coerce} } sub get_read_method { $_[0]->{reader} || $_[0]->{accessor} } sub get_write_method { $_[0]->{writer} || $_[0]->{accessor} } # predicates sub has_accessor { exists $_[0]->{accessor} } sub has_reader { exists $_[0]->{reader} } sub has_writer { exists $_[0]->{writer} } sub has_predicate { exists $_[0]->{predicate} } sub has_clearer { exists $_[0]->{clearer} } sub has_handles { exists $_[0]->{handles} } sub has_default { exists $_[0]->{default} } sub has_type_constraint { exists $_[0]->{type_constraint} } sub has_trigger { exists $_[0]->{trigger} } sub has_builder { exists $_[0]->{builder} } sub has_read_method { exists $_[0]->{reader} || exists $_[0]->{accessor} } sub has_write_method { exists $_[0]->{writer} || exists $_[0]->{accessor} } sub _create_args { $_[0]->{_create_args} = $_[1] if @_ > 1; $_[0]->{_create_args} } sub interpolate_class{ my($class, $name, $args) = @_; if(my $metaclass = delete $args->{metaclass}){ $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass ); } my @traits; if(my $traits_ref = delete $args->{traits}){ for (my $i = 0; $i < @{$traits_ref}; $i++) { my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1); next if $class->does($trait); push @traits, $trait; # are there options? push @traits, $traits_ref->[++$i] if ref($traits_ref->[$i+1]); } if (@traits) { $class = Mouse::Meta::Class->create_anon_class( superclasses => [ $class ], roles => \@traits, cache => 1, )->name; } } return( $class, @traits ); } sub canonicalize_args{ my ($self, $name, %args) = @_; Carp::cluck("$self->canonicalize_args has been deprecated." . "Use \$self->_process_options instead."); return %args; } sub create { my ($self, $class, $name, %args) = @_; Carp::cluck("$self->create has been deprecated." . "Use \$meta->add_attribute and \$attr->install_accessors instead."); # noop return $self; } sub verify_against_type_constraint { my ($self, $value) = @_; my $tc = $self->type_constraint; return 1 unless $tc; local $_ = $value; return 1 if $tc->check($value); $self->verify_type_constraint_error($self->name, $value, $tc); } sub verify_type_constraint_error { my($self, $name, $value, $type) = @_; $self->throw_error("Attribute ($name) does not pass the type constraint because: " . $type->get_message($value)); } sub coerce_constraint { ## my($self, $value) = @_; my $type = $_[0]->{type_constraint} or return $_[1]; return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $type, $_[1]); } sub _canonicalize_handles { my $self = shift; my $handles = shift; if (ref($handles) eq 'HASH') { return %$handles; } elsif (ref($handles) eq 'ARRAY') { return map { $_ => $_ } @$handles; } else { $self->throw_error("Unable to canonicalize the 'handles' option with $handles"); } } sub clone_and_inherit_options{ my $self = shift; my $name = shift; return ref($self)->new($name, %{$self}, (@_ == 1) ? %{$_[0]} : @_); } sub clone_parent { my $self = shift; my $class = shift; my $name = shift; my %args = ($self->get_parent_args($class, $name), @_); Carp::cluck("$self->clone_parent has been deprecated." . "Use \$meta->add_attribute and \$attr->install_accessors instead."); $self->clone_and_inherited_args($class, $name, %args); } sub get_parent_args { my $self = shift; my $class = shift; my $name = shift; for my $super ($class->linearized_isa) { my $super_attr = $super->can("meta") && $super->meta->get_attribute($name) or next; return %{ $super_attr->_create_args }; } $self->throw_error("Could not find an attribute by the name of '$name' to inherit from"); } sub install_accessors{ my($attribute) = @_; my $metaclass = $attribute->{associated_class}; foreach my $type(qw(accessor reader writer predicate clearer handles)){ if(exists $attribute->{$type}){ my $installer = '_install_' . $type; Mouse::Meta::Method::Accessor->$installer($attribute, $attribute->{$type}, $metaclass); $attribute->{associated_methods}++; } } if($attribute->can('create') != \&create){ # backword compatibility $attribute->create($metaclass, $attribute->name, %{$attribute}); } return; } sub throw_error{ my $self = shift; my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class'; $metaclass->throw_error(@_, depth => 1); } 1; __END__ =head1 NAME Mouse::Meta::Attribute - attribute metaclass =head1 METHODS =head2 C<< new(%options) -> Mouse::Meta::Attribute >> Instantiates a new Mouse::Meta::Attribute. Does nothing else. It adds the following options to the constructor: =over 4 =item * C<< is => 'ro', 'rw', 'bare' >> This provides a shorthand for specifying the C, C, or C names. If the attribute is read-only ('ro') then it will have a C method with the same attribute as the name. If it is read-write ('rw') then it will have an C method with the same name. If you provide an explicit C for a read-write attribute, then you will have a C with the same name as the attribute, and a C with the name you provided. Use 'bare' when you are deliberately not installing any methods (accessor, reader, etc.) associated with this attribute; otherwise, Moose will issue a deprecation warning when this attribute is added to a metaclass. =item * C<< isa => Type >> This option accepts a type. The type can be a string, which should be a type name. If the type name is unknown, it is assumed to be a class name. This option can also accept a L object. If you I provide a C option, then your C option must be a class name, and that class must do the role specified with C. =item * C<< does => Role >> This is short-hand for saying that the attribute's type must be an object which does the named role. B =item * C<< coerce => Bool >> This option is only valid for objects with a type constraint (C). If this is true, then coercions will be applied whenever this attribute is set. You can make both this and the C option true. =item * C<< trigger => CodeRef >> This option accepts a subroutine reference, which will be called after the attribute is set. =item * C<< required => Bool >> An attribute which is required must be provided to the constructor. An attribute which is required can also have a C or C, which will satisfy its required-ness. A required attribute must have a C, C or a non-C C =item * C<< lazy => Bool >> A lazy attribute must have a C or C. When an attribute is lazy, the default value will not be calculated until the attribute is read. =item * C<< weak_ref => Bool >> If this is true, the attribute's value will be stored as a weak reference. =item * C<< auto_deref => Bool >> If this is true, then the reader will dereference the value when it is called. The attribute must have a type constraint which defines the attribute as an array or hash reference. =item * C<< lazy_build => Bool >> Setting this to true makes the attribute lazy and provides a number of default methods. has 'size' => ( is => 'ro', lazy_build => 1, ); is equivalent to this: has 'size' => ( is => 'ro', lazy => 1, builder => '_build_size', clearer => 'clear_size', predicate => 'has_size', ); =back =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >> Checks that the given value passes this attribute's type constraint. Returns C on success, otherwise Ces. =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >> Creates a new attribute in OwnerClass, inheriting options from parent classes. Accessors and helper methods are installed. Some error checking is done. =head1 SEE ALSO L =cut