use strict;
use warnings;
-use Scalar::Util 'blessed', 'weaken', 'reftype';
-use Carp 'confess';
-use Sub::Name 'subname';
+use Scalar::Util 'blessed', 'weaken';
use overload ();
-our $VERSION = '0.22';
+our $VERSION = '0.75_01';
our $AUTHORITY = 'cpan:STEVAN';
use Moose::Meta::Method::Accessor;
+use Moose::Meta::Method::Delegation;
+use Moose::Util ();
use Moose::Util::TypeConstraints ();
use base 'Class::MOP::Attribute';
predicate => 'has_applied_traits',
));
-# NOTE:
# we need to have a ->does method in here to
# more easily support traits, and the introspection
-# of those traits. So in order to do this we
-# just alias Moose::Object's version of it.
-# - SL
-*does = \&Moose::Object::does;
+# of those traits. We extend the does check to look
+# for metatrait aliases.
+sub does {
+ my ($self, $role_name) = @_;
+ my $name = eval {
+ Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
+ };
+ return 0 if !defined($name); # failed to load class
+ return $self->Moose::Object::does($name);
+}
+
+sub throw_error {
+ my $self = shift;
+ my $class = ( ref $self && $self->associated_class ) || "Moose::Meta::Class";
+ unshift @_, "message" if @_ % 2 == 1;
+ unshift @_, attr => $self if ref $self;
+ unshift @_, $class;
+ my $handler = $class->can("throw_error"); # to avoid incrementing depth by 1
+ goto $handler;
+}
sub new {
my ($class, $name, %options) = @_;
- $class->_process_options($name, \%options);
+ $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS
return $class->SUPER::new($name, %options);
}
+sub interpolate_class_and_new {
+ my ($class, $name, @args) = @_;
+
+ my ( $new_class, @traits ) = $class->interpolate_class(@args);
+
+ $new_class->new($name, @args, ( scalar(@traits) ? ( traits => \@traits ) : () ) );
+}
+
+sub interpolate_class {
+ my ($class, %options) = @_;
+
+ $class = ref($class) || $class;
+
+ if ( my $metaclass_name = delete $options{metaclass} ) {
+ my $new_class = Moose::Util::resolve_metaclass_alias( Attribute => $metaclass_name );
+
+ if ( $class ne $new_class ) {
+ if ( $new_class->can("interpolate_class") ) {
+ return $new_class->interpolate_class(%options);
+ } else {
+ $class = $new_class;
+ }
+ }
+ }
+
+ my @traits;
+
+ if (my $traits = $options{traits}) {
+ my $i = 0;
+ while ($i < @$traits) {
+ my $trait = $traits->[$i++];
+ next if ref($trait); # options to a trait we discarded
+
+ $trait = Moose::Util::resolve_metatrait_alias(Attribute => $trait)
+ || $trait;
+
+ next if $class->does($trait);
+
+ push @traits, $trait;
+
+ # are there options?
+ push @traits, $traits->[$i++]
+ if $traits->[$i] && ref($traits->[$i]);
+ }
+
+ if (@traits) {
+ my $anon_class = Moose::Meta::Class->create_anon_class(
+ superclasses => [ $class ],
+ roles => [ @traits ],
+ cache => 1,
+ );
+
+ $class = $anon_class->name;
+ }
+ }
+
+ return ( wantarray ? ( $class, @traits ) : $class );
+}
+
+# ...
+
+my @legal_options_for_inheritance = qw(
+ default coerce required
+ documentation lazy handles
+ builder type_constraint
+ definition_context
+ lazy_build
+);
+
+sub legal_options_for_inheritance { @legal_options_for_inheritance }
+
+# NOTE/TODO
+# This method *must* be able to handle
+# Class::MOP::Attribute instances as
+# well. Yes, I know that is wrong, but
+# apparently we didn't realize it was
+# doing that and now we have some code
+# which is dependent on it. The real
+# solution of course is to push this
+# feature back up into Class::MOP::Attribute
+# but I not right now, I am too lazy.
+# However if you are reading this and
+# looking for something to do,.. please
+# be my guest.
+# - stevan
sub clone_and_inherit_options {
my ($self, %options) = @_;
- # you can change default, required, coerce, documentation, lazy, handles, builder, metaclass and traits
+
+ my %copy = %options;
+
my %actual_options;
- foreach my $legal_option (qw(default coerce required documentation lazy handles builder metaclass traits)) {
+
+ # NOTE:
+ # we may want to extends a Class::MOP::Attribute
+ # in which case we need to be able to use the
+ # core set of legal options that have always
+ # been here. But we allows Moose::Meta::Attribute
+ # instances to changes them.
+ # - SL
+ my @legal_options = $self->can('legal_options_for_inheritance')
+ ? $self->legal_options_for_inheritance
+ : @legal_options_for_inheritance;
+
+ foreach my $legal_option (@legal_options) {
if (exists $options{$legal_option}) {
$actual_options{$legal_option} = $options{$legal_option};
delete $options{$legal_option};
}
- }
+ }
if ($options{isa}) {
my $type_constraint;
else {
$type_constraint = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options{isa});
(defined $type_constraint)
- || confess "Could not find the type constraint '" . $options{isa} . "'";
+ || $self->throw_error("Could not find the type constraint '" . $options{isa} . "'", data => $options{isa});
}
$actual_options{type_constraint} = $type_constraint;
else {
$type_constraint = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options{does});
(defined $type_constraint)
- || confess "Could not find the type constraint '" . $options{does} . "'";
+ || $self->throw_error("Could not find the type constraint '" . $options{does} . "'", data => $options{does});
}
$actual_options{type_constraint} = $type_constraint;
delete $options{does};
}
-
+
+ # NOTE:
+ # this doesn't apply to Class::MOP::Attributes,
+ # so we can ignore it for them.
+ # - SL
+ if ($self->can('interpolate_class')) {
+ ( $actual_options{metaclass}, my @traits ) = $self->interpolate_class(%options);
+
+ my %seen;
+ my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
+ $actual_options{traits} = \@all_traits if @all_traits;
+
+ delete @options{qw(metaclass traits)};
+ }
+
(scalar keys %options == 0)
- || confess "Illegal inherited options => (" . (join ', ' => keys %options) . ")";
+ || $self->throw_error("Illegal inherited options => (" . (join ', ' => keys %options) . ")", data => \%options);
+
+
$self->clone(%actual_options);
}
+sub clone {
+ my ( $self, %params ) = @_;
+
+ my $class = $params{metaclass} || ref $self;
+
+ my ( @init, @non_init );
+
+ foreach my $attr ( grep { $_->has_value($self) } Class::MOP::class_of($self)->get_all_attributes ) {
+ push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
+ }
+
+ my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );
+
+ my $name = delete $new_params{name};
+
+ my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );
+
+ foreach my $attr ( @non_init ) {
+ $attr->set_value($clone, $attr->get_value($self));
+ }
+
+ return $clone;
+}
+
sub _process_options {
my ($class, $name, $options) = @_;
if (exists $options->{is}) {
+
+ ### -------------------------
+ ## is => ro, writer => _foo # turns into (reader => foo, writer => _foo) as before
+ ## is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
+ ## is => rw, accessor => _foo # turns into (accessor => _foo)
+ ## is => ro, accessor => _foo # error, accesor is rw
+ ### -------------------------
+
if ($options->{is} eq 'ro') {
+ $class->throw_error("Cannot define an accessor name on a read-only attribute, accessors are read/write", data => $options)
+ if exists $options->{accessor};
$options->{reader} ||= $name;
- (!exists $options->{trigger})
- || confess "Cannot have a trigger on a read-only attribute $name";
}
elsif ($options->{is} eq 'rw') {
- $options->{accessor} = $name;
- ((reftype($options->{trigger}) || '') eq 'CODE')
- || confess "Trigger must be a CODE ref"
- if exists $options->{trigger};
+ if ($options->{writer}) {
+ $options->{reader} ||= $name;
+ }
+ else {
+ $options->{accessor} ||= $name;
+ }
}
else {
- confess "I do not understand this option (is => " . $options->{is} . ") on attribute $name"
+ $class->throw_error("I do not understand this option (is => " . $options->{is} . ") on attribute ($name)", data => $options->{is});
}
}
if (exists $options->{does}) {
if (eval { $options->{isa}->can('does') }) {
($options->{isa}->does($options->{does}))
- || confess "Cannot have an isa option and a does option if the isa does not do the does on attribute $name";
+ || $class->throw_error("Cannot have an isa option and a does option if the isa does not do the does on attribute ($name)", data => $options);
}
else {
- confess "Cannot have an isa option which cannot ->does() on attribute $name";
+ $class->throw_error("Cannot have an isa option which cannot ->does() on attribute ($name)", data => $options);
}
}
if (exists $options->{coerce} && $options->{coerce}) {
(exists $options->{type_constraint})
- || confess "You cannot have coercion without specifying a type constraint on attribute $name";
- confess "You cannot have a weak reference to a coerced value on attribute $name"
+ || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)", data => $options);
+ $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)", data => $options)
if $options->{weak_ref};
}
+ if (exists $options->{trigger}) {
+ ('CODE' eq ref $options->{trigger})
+ || $class->throw_error("Trigger must be a CODE ref on attribute ($name)", data => $options->{trigger});
+ }
+
if (exists $options->{auto_deref} && $options->{auto_deref}) {
(exists $options->{type_constraint})
- || confess "You cannot auto-dereference without specifying a type constraint on attribute $name";
+ || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)", data => $options);
($options->{type_constraint}->is_a_type_of('ArrayRef') ||
$options->{type_constraint}->is_a_type_of('HashRef'))
- || confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute $name";
+ || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)", data => $options);
}
if (exists $options->{lazy_build} && $options->{lazy_build} == 1) {
- confess("You can not use lazy_build and default for the same attribute $name")
+ $class->throw_error("You can not use lazy_build and default for the same attribute ($name)", data => $options)
if exists $options->{default};
$options->{lazy} = 1;
$options->{required} = 1;
if (exists $options->{lazy} && $options->{lazy}) {
(exists $options->{default} || defined $options->{builder} )
- || confess "You cannot have lazy attribute ($name) without specifying a default value for it";
+ || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it", data => $options);
}
if ( $options->{required} && !( ( !exists $options->{init_arg} || defined $options->{init_arg} ) || exists $options->{default} || defined $options->{builder} ) ) {
- confess "You cannot have a required attribute ($name) without a default, builder, or an init_arg";
+ $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg", data => $options);
}
}
# skip it if it's lazy
return if $self->is_lazy;
# and die if it's required and doesn't have a default value
- confess "Attribute (" . $self->name . ") is required"
+ $self->throw_error("Attribute (" . $self->name . ") is required", object => $instance, data => $params)
if $self->is_required && !$self->has_default && !$self->has_builder;
# if nothing was in the %params, we can use the
$value_is_set = 1;
}
elsif ($self->has_builder) {
- if (my $builder = $instance->can($self->builder)){
- $val = $instance->$builder;
- $value_is_set = 1;
- }
- else {
- confess(blessed($instance)." does not support builder method '".$self->builder."' for attribute '" . $self->name . "'");
- }
+ $val = $self->_call_builder($instance);
+ $value_is_set = 1;
}
}
return unless $value_is_set;
- if ($self->has_type_constraint) {
- my $type_constraint = $self->type_constraint;
- if ($self->should_coerce && $type_constraint->has_coercion) {
- $val = $type_constraint->coerce($val);
- }
- $type_constraint->check($val)
- || confess "Attribute ("
- . $self->name
- . ") does not pass the type constraint because: "
- . $type_constraint->get_message($val);
- }
+ $val = $self->_coerce_and_verify( $val, $instance );
$self->set_initial_value($instance, $val);
$meta_instance->weaken_slot_value($instance, $self->name)
if ref $val && $self->is_weak_ref;
}
+sub _call_builder {
+ my ( $self, $instance ) = @_;
+
+ my $builder = $self->builder();
+
+ return $instance->$builder()
+ if $instance->can( $self->builder );
+
+ $self->throw_error( blessed($instance)
+ . " does not support builder method '"
+ . $self->builder
+ . "' for attribute '"
+ . $self->name
+ . "'",
+ object => $instance,
+ );
+}
+
## Slot management
# FIXME:
}
my $callback = sub {
- my $val = shift;
- if ($type_constraint) {
- $val = $type_constraint->coerce($val)
- if $can_coerce;
- $type_constraint->check($val)
- || confess "Attribute ("
- . $slot_name
- . ") does not pass the type constraint because: "
- . $type_constraint->get_message($val);
- }
+ my $val = $self->_coerce_and_verify( shift, $instance );;
+
$meta_instance->set_slot_value($instance, $slot_name, $val);
};
}
sub set_value {
- my ($self, $instance, $value) = @_;
+ my ($self, $instance, @args) = @_;
+ my $value = $args[0];
my $attr_name = $self->name;
- if ($self->is_required) {
- defined($value)
- || confess "Attribute ($attr_name) is required, so cannot be set to undef";
+ if ($self->is_required and not @args) {
+ $self->throw_error("Attribute ($attr_name) is required", object => $instance);
}
- if ($self->has_type_constraint) {
-
- my $type_constraint = $self->type_constraint;
-
- if ($self->should_coerce) {
- $value = $type_constraint->coerce($value);
- }
- $type_constraint->_compiled_type_constraint->($value)
- || confess "Attribute ("
- . $self->name
- . ") does not pass the type constraint because "
- . $type_constraint->get_message($value);
- }
+ $value = $self->_coerce_and_verify( $value, $instance );
my $meta_instance = Class::MOP::Class->initialize(blessed($instance))
->get_meta_instance;
}
if ($self->has_trigger) {
- $self->trigger->($instance, $value, $self);
+ $self->trigger->($instance, $value);
}
}
if ($self->is_lazy) {
unless ($self->has_value($instance)) {
+ my $value;
if ($self->has_default) {
- my $default = $self->default($instance);
- $self->set_initial_value($instance, $default);
- }
- if ( $self->has_builder ){
- if (my $builder = $instance->can($self->builder)){
- $self->set_initial_value($instance, $instance->$builder);
- }
- else {
- confess(blessed($instance)
- . " does not support builder method '"
- . $self->builder
- . "' for attribute '"
- . $self->name
- . "'");
- }
- }
- else {
- $self->set_initial_value($instance, undef);
+ $value = $self->default($instance);
+ } elsif ( $self->has_builder ) {
+ $value = $self->_call_builder($instance);
}
+
+ $value = $self->_coerce_and_verify( $value, $instance );
+
+ $self->set_initial_value($instance, $value);
}
}
return wantarray ? %{ $rv } : $rv;
}
else {
- confess "Can not auto de-reference the type constraint '" . $type_constraint->name . "'";
+ $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
}
}
sub install_accessors {
my $self = shift;
$self->SUPER::install_accessors(@_);
+ $self->install_delegation if $self->has_handles;
+ return;
+}
+
+sub remove_accessors {
+ my $self = shift;
+ $self->SUPER::remove_accessors(@_);
+ $self->remove_delegation if $self->has_handles;
+ return;
+}
- if ($self->has_handles) {
+sub install_delegation {
+ my $self = shift;
+
+ # NOTE:
+ # Here we canonicalize the 'handles' option
+ # this will sort out any details and always
+ # return an hash of methods which we want
+ # to delagate to, see that method for details
+ my %handles = $self->_canonicalize_handles;
- # NOTE:
- # Here we canonicalize the 'handles' option
- # this will sort out any details and always
- # return an hash of methods which we want
- # to delagate to, see that method for details
- my %handles = $self->_canonicalize_handles();
-
- # find the accessor method for this attribute
- my $accessor = $self->get_read_method_ref;
- # then unpack it if we need too ...
- $accessor = $accessor->body if blessed $accessor;
-
- # install the delegation ...
- my $associated_class = $self->associated_class;
- foreach my $handle (keys %handles) {
- my $method_to_call = $handles{$handle};
- my $class_name = $associated_class->name;
- my $name = "${class_name}::${handle}";
+
+ # install the delegation ...
+ my $associated_class = $self->associated_class;
+ foreach my $handle (keys %handles) {
+ my $method_to_call = $handles{$handle};
+ my $class_name = $associated_class->name;
+ my $name = "${class_name}::${handle}";
(!$associated_class->has_method($handle))
- || confess "You cannot overwrite a locally defined method ($handle) with a delegation";
+ || $self->throw_error("You cannot overwrite a locally defined method ($handle) with a delegation", method_name => $handle);
- # NOTE:
- # handles is not allowed to delegate
- # any of these methods, as they will
- # override the ones in your class, which
- # is almost certainly not what you want.
+ # NOTE:
+ # handles is not allowed to delegate
+ # any of these methods, as they will
+ # override the ones in your class, which
+ # is almost certainly not what you want.
- # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
- #cluck("Not delegating method '$handle' because it is a core method") and
- next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
+ # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
+ #cluck("Not delegating method '$handle' because it is a core method") and
+ next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
- if ((reftype($method_to_call) || '') eq 'CODE') {
- $associated_class->add_method($handle => subname $name, $method_to_call);
- }
- else {
- # NOTE:
- # we used to do a goto here, but the
- # goto didn't handle failure correctly
- # (it just returned nothing), so I took
- # that out. However, the more I thought
- # about it, the less I liked it doing
- # the goto, and I prefered the act of
- # delegation being actually represented
- # in the stack trace.
- # - SL
- $associated_class->add_method($handle => subname $name, sub {
- my $proxy = (shift)->$accessor();
- (defined $proxy)
- || confess "Cannot delegate $handle to $method_to_call because " .
- "the value of " . $self->name . " is not defined";
- $proxy->$method_to_call(@_);
- });
- }
- }
- }
+ my $method = $self->_make_delegation_method($handle, $method_to_call);
- return;
+ $self->associated_class->add_method($method->name, $method);
+ }
+}
+
+sub remove_delegation {
+ my $self = shift;
+ my %handles = $self->_canonicalize_handles;
+ my $associated_class = $self->associated_class;
+ foreach my $handle (keys %handles) {
+ $self->associated_class->remove_method($handle);
+ }
}
# private methods to help delegation ...
}
elsif ($handle_type eq 'Regexp') {
($self->has_type_constraint)
- || confess "Cannot delegate methods based on a RegExpr without a type constraint (isa)";
+ || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
return map { ($_ => $_) }
grep { /$handles/ } $self->_get_delegate_method_list;
}
return $handles->($self, $self->_find_delegate_metaclass);
}
else {
- confess "Unable to canonicalize the 'handles' option with $handles";
+ $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
}
}
else {
- my $role_meta = eval { $handles->meta };
- if ($@) {
- confess "Unable to canonicalize the 'handles' option with $handles because : $@";
- }
+ my $role_meta = Class::MOP::load_class($handles);
(blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
- || confess "Unable to canonicalize the 'handles' option with $handles because ->meta is not a Moose::Meta::Role";
-
+ || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
+
return map { $_ => $_ } (
$role_meta->get_method_list,
$role_meta->get_required_method_list
sub _find_delegate_metaclass {
my $self = shift;
if (my $class = $self->_isa_metadata) {
- # if the class does have
- # a meta method, use it
- return $class->meta if $class->can('meta');
- # otherwise we might be
- # dealing with a non-Moose
- # class, and need to make
- # our own metaclass
+ # we might be dealing with a non-Moose class,
+ # and need to make our own metaclass. if there's
+ # already a metaclass, it will be returned
return Moose::Meta::Class->initialize($class);
}
elsif (my $role = $self->_does_metadata) {
- # our role will always have
- # a meta method
- return $role->meta;
+ return Class::MOP::class_of($role);
}
else {
- confess "Cannot find delegate metaclass for attribute " . $self->name;
+ $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
}
}
my $self = shift;
my $meta = $self->_find_delegate_metaclass;
if ($meta->isa('Class::MOP::Class')) {
- return map { $_->{name} } # NOTE: !never! delegate &meta
- grep { $_->{class} ne 'Moose::Object' && $_->{name} ne 'meta' }
- $meta->compute_all_applicable_methods;
+ return map { $_->name } # NOTE: !never! delegate &meta
+ grep { $_->package_name ne 'Moose::Object' && $_->name ne 'meta' }
+ $meta->get_all_methods;
}
elsif ($meta->isa('Moose::Meta::Role')) {
return $meta->get_method_list;
}
else {
- confess "Unable to recognize the delegate metaclass '$meta'";
+ $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
}
}
+sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
+
+sub _make_delegation_method {
+ my ( $self, $handle_name, $method_to_call ) = @_;
+
+ my $method_body;
+
+ $method_body = $method_to_call
+ if 'CODE' eq ref($method_to_call);
+
+ return $self->delegation_metaclass->new(
+ name => $handle_name,
+ package_name => $self->associated_class->name,
+ attribute => $self,
+ delegate_to_method => $method_to_call,
+ );
+}
+
+sub _coerce_and_verify {
+ my $self = shift;
+ my $val = shift;
+ my $instance = shift;
+
+ return $val unless $self->has_type_constraint;
+
+ my $type_constraint = $self->type_constraint;
+ if ($self->should_coerce && $type_constraint->has_coercion) {
+ $val = $type_constraint->coerce($val);
+ }
+
+ $self->verify_against_type_constraint($val, instance => $instance);
+
+ return $val;
+}
+
+sub verify_against_type_constraint {
+ my $self = shift;
+ my $val = shift;
+
+ return 1 if !$self->has_type_constraint;
+
+ my $type_constraint = $self->type_constraint;
+
+ $type_constraint->check($val)
+ || $self->throw_error("Attribute ("
+ . $self->name
+ . ") does not pass the type constraint because: "
+ . $type_constraint->get_message($val), data => $val, @_);
+}
+
+package Moose::Meta::Attribute::Custom::Moose;
+sub register_implementation { 'Moose::Meta::Attribute' }
+
1;
__END__
=head1 DESCRIPTION
-This is a subclass of L<Class::MOP::Attribute> with Moose specific
-extensions.
+This class is a subclass of L<Class::MOP::Attribute> that provides
+additional Moose-specific functionality.
+
+To really understand this class, you will need to start with the
+L<Class::MOP::Attribute> documentation. This class can be understood
+as a set of additional features on top of the basic feature provided
+by that parent class.
+
+=head1 INHERITANCE
-For the most part, the only time you will ever encounter an
-instance of this class is if you are doing some serious deep
-introspection. To really understand this class, you need to refer
-to the L<Class::MOP::Attribute> documentation.
+C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
=head1 METHODS
-=head2 Overridden methods
+Many of the documented below override methods in
+L<Class::MOP::Attribute> and add Moose specific features.
-These methods override methods in L<Class::MOP::Attribute> and add
-Moose specific features. You can safely assume though that they
-will behave just as L<Class::MOP::Attribute> does.
+=head2 Creation
=over 4
-=item B<new>
+=item B<< Moose::Meta::Attribute->new(%options) >>
+
+This method overrides the L<Class::MOP::Attribute> constructor.
+
+Many of the options below are described in more detail in the
+L<Moose::Manual::Attributes> document.
+
+It adds the following options to the constructor:
+
+=over 8
+
+=item * is => 'ro' or 'rw'
+
+This provides a shorthand for specifying the C<reader>, C<writer>, or
+C<accessor> names. If the attribute is read-only ('ro') then it will
+have a C<reader> method with the same attribute as the name.
+
+If it is read-write ('rw') then it will have an C<accessor> method
+with the same name. If you provide an explicit C<writer> for a
+read-write attribute, then you will have a C<reader> with the same
+name as the attribute, and a C<writer> with the name you provided.
+
+=item * 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<Moose::Meta::TypeConstraint> object.
+
+If you I<also> provide a C<does> option, then your C<isa> option must
+be a class name, and that class must do the role specified with
+C<does>.
+
+=item * does => $role
+
+This is short-hand for saying that the attribute's type must be an
+object which does the named role.
+
+=item * coerce => $bool
+
+This option is only valid for objects with a type constraint
+(C<isa>). If this is true, then coercions will be applied whenever
+this attribute is set.
+
+You can make both this and the C<weak_ref> option true.
+
+=item * trigger => $sub
+
+This option accepts a subroutine reference, which will be called after
+the attribute is set.
-=item B<does>
+=item * required => $bool
-=item B<initialize_instance_slot>
+An attribute which is required must be provided to the constructor. An
+attribute which is required can also have a C<default> or C<builder>,
+which will satisfy its required-ness.
-=item B<install_accessors>
+A required attribute must have a C<default>, C<builder> or a
+non-C<undef> C<init_arg>
-=item B<accessor_metaclass>
+=item * lazy => $bool
+
+A lazy attribute must have a C<default> or C<builder>. When an
+attribute is lazy, the default value will not be calculated until the
+attribute is read.
+
+=item * weak_ref => $bool
+
+If this is true, the attribute's value will be stored as a weak
+reference.
+
+=item * 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 * lazy_build => $bool
+
+Setting this to true makes the attribute lazy and provides a number of
+default methods.
+
+ has 'size' => (
+ is => 'ro',
+ lazy_build => 1,
+ );
+
+is equivalent to this:
+
+ has 'size' => (
+ is => 'ro',
+ lazy => 1,
+ builder => '_build_size',
+ clearer => 'clear_size',
+ predicate => 'has_size',
+ );
+
+=item * documentation
+
+An arbitrary string that can be retrieved later by calling C<<
+$attr->documentation >>.
+
+=back
+
+=item B<< $attr->clone(%options) >>
+
+This creates a new attribute based on attribute being cloned. You must
+supply a C<name> option to provide a new name for the attribute.
+
+The C<%options> can only specify options handled by
+L<Class::MOP::Attribute>.
+
+=back
+
+=head2 Value management
+
+=over 4
+
+=item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
+
+This method is used internally to initialize the attribute's slot in
+the object C<$instance>.
+
+This overrides the L<Class::MOP::Attribute> method to handle lazy
+attributes, weak references, and type constraints.
=item B<get_value>
=item B<set_value>
- eval { $point->meta->get_attribute('x')->set_value($point, 'fourty-two') };
+ eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
if($@) {
print "Oops: $@\n";
}
-I<Attribute (x) does not pass the type constraint (Int) with 'fourty-two'>
+I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
Before setting the value, a check is made on the type constraint of
the attribute, if it has one, to see if the value passes it. If the
-value fails to pass, the set operation dies with a L<Carp/confess>.
+value fails to pass, the set operation dies with a L<throw_error>.
Any coercion to convert values is done before checking the type constraint.
To check a value against a type constraint before setting it, fetch the
attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
-and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::RecipeX>
+and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
for an example.
=back
+=head2 Attribute Accessor generation
+
+=over 4
+
+=item B<< $attr->install_accessors >>
+
+This method overrides the parent to also install delegation methods.
+
+=item B<< $attr->remove_accessors >>
+
+This method overrides the parent to also remove delegation methods.
+
+=item B<< $attr->install_delegation >>
+
+This method adds its delegation methods to the attribute's associated
+class, if it has any to add.
+
+=item B<< $attr->remove_delegation >>
+
+This method remove its delegation methods from the attribute's
+associated class.
+
+=item B<< $attr->accessor_metaclass >>
+
+Returns the accessor metaclass name, which defaults to
+L<Moose::Meta::Method::Accessor>.
+
+=item B<< $attr->delegation_metaclass >>
+
+Returns the delegation metaclass name, which defaults to
+L<Moose::Meta::Method::Delegation>.
+
+=back
+
=head2 Additional Moose features
-Moose attributes support type-constraint checking, weak reference
-creation and type coercion.
+These methods are not found in the superclass. They support features
+provided by Moose.
=over 4
-=item B<clone_and_inherit_options>
+=item B<< $attr->does($role) >>
+
+This indicates whether the I<attribute itself> does the given
+role. The role can be given as a full class name, or as a resolvable
+trait name.
+
+Note that this checks the attribute itself, not its type constraint,
+so it is checking the attribute's metaclass and any traits applied to
+the attribute.
+
+=item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
+
+This is an alternate constructor that handles the C<metaclass> and
+C<traits> options.
+
+Effectively, this method is a factory that finds or creates the
+appropriate class for the given C<metaclass> and/or C<traits>.
+
+Once it has the appropriate class, it will call C<< $class->new($name,
+%options) >> on that class.
+
+=item B<< $attr->clone_and_inherit_options(%options) >>
-This is to support the C<has '+foo'> feature, it clones an attribute
-from a superclass and allows a very specific set of changes to be made
-to the attribute.
+This method supports the C<has '+foo'> feature. It does various bits
+of processing on the supplied C<%options> before ultimately calling
+the C<clone> method.
-=item B<has_type_constraint>
+One of its main tasks is to make sure that the C<%options> provided
+only includes the options returned by the
+C<legal_options_for_inheritance> method.
-Returns true if this meta-attribute has a type constraint.
+=item B<< $attr->legal_options_for_inheritance >>
-=item B<type_constraint>
+This returns a whitelist of options that can be overridden in a
+subclass's attribute definition.
-A read-only accessor for this meta-attribute's type constraint. For
-more information on what you can do with this, see the documentation
-for L<Moose::Meta::TypeConstraint>.
+This exists to allow a custom metaclass to change or add to the list
+of options which can be changed.
-=item B<has_handles>
+=item B<< $attr->type_constraint >>
-Returns true if this meta-attribute performs delegation.
+Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
+if it has one.
-=item B<handles>
+=item B<< $attr->has_type_constraint >>
-This returns the value which was passed into the handles option.
+Returns true if this attribute has a type constraint.
-=item B<is_weak_ref>
+=item B<< $attr->verify_against_type_constraint($value) >>
-Returns true if this meta-attribute produces a weak reference.
+Given a value, this method returns true if the value is valid for the
+attribute's type constraint. If the value is not valid, it throws an
+error.
-=item B<is_required>
+=item B<< $attr->handles >>
-Returns true if this meta-attribute is required to have a value.
+This returns the value of the C<handles> option passed to the
+constructor.
-=item B<is_lazy>
+=item B<< $attr->has_handles >>
-Returns true if this meta-attribute should be initialized lazily.
+Returns true if this attribute performs delegation.
-NOTE: lazy attributes, B<must> have a C<default> or C<builder> field set.
+=item B<< $attr->is_weak_ref >>
-=item B<is_lazy_build>
+Returns true if this attribute stores its value as a weak reference.
-Returns true if this meta-attribute should be initialized lazily through
-the builder generated by lazy_build. Using C<lazy_build =E<gt> 1> will
-make your attribute required and lazy. In addition it will set the builder, clearer
-and predicate options for you using the following convention.
+=item B<< $attr->is_required >>
- #If your attribute name starts with an underscore:
- has '_foo' => (lazy_build => 1);
- #is the same as
- has '_foo' => (lazy => 1, required => 1, predicate => '_has_foo', clearer => '_clear_foo', builder => '_build__foo);
- # or
- has '_foo' => (lazy => 1, required => 1, predicate => '_has_foo', clearer => '_clear_foo', default => sub{shift->_build__foo});
+Returns true if this attribute is required to have a value.
- #If your attribute name does not start with an underscore:
- has 'foo' => (lazy_build => 1);
- #is the same as
- has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', builder => '_build_foo);
- # or
- has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', default => sub{shift->_build_foo});
+=item B<< $attr->is_lazy >>
-The reason for the different naming of the C<builder> is that the C<builder>
-method is a private method while the C<clearer> and C<predicate> methods
-are public methods.
+Returns true if this attribute is lazy.
-NOTE: This means your class should provide a method whose name matches the value
-of the builder part, in this case _build__foo or _build_foo.
+=item B<< $attr->is_lazy_build >>
-=item B<should_coerce>
+Returns true if the C<lazy_build> option was true when passed to the
+constructor.
-Returns true if this meta-attribute should perform type coercion.
+=item B<< $attr->should_coerce >>
-=item B<should_auto_deref>
+Returns true if the C<coerce> option passed to the constructor was
+true.
-Returns true if this meta-attribute should perform automatic
-auto-dereferencing.
+=item B<< $attr->should_auto_deref >>
-NOTE: This can only be done for attributes whose type constraint is
-either I<ArrayRef> or I<HashRef>.
+Returns true if the C<auto_deref> option passed to the constructor was
+true.
-=item B<has_trigger>
+=item B<< $attr->trigger >>
-Returns true if this meta-attribute has a trigger set.
+This is the subroutine reference that was in the C<trigger> option
+passed to the constructor, if any.
-=item B<trigger>
+=item B<< $attr->has_trigger >>
-This is a CODE reference which will be executed every time the
-value of an attribute is assigned. The CODE ref will get two values,
-the invocant and the new value. This can be used to handle I<basic>
-bi-directional relations.
+Returns true if this attribute has a trigger set.
-=item B<documentation>
+=item B<< $attr->documentation >>
-This is a string which contains the documentation for this attribute.
-It serves no direct purpose right now, but it might in the future
-in some kind of automated documentation system perhaps.
+Returns the value that was in the C<documentation> option passed to
+the constructor, if any.
-=item B<has_documentation>
+=item B<< $attr->has_documentation >>
-Returns true if this meta-attribute has any documentation.
+Returns true if this attribute has any documentation.
-=item B<applied_traits>
+=item B<< $attr->applied_traits >>
-This will return the ARRAY ref of all the traits applied to this
-attribute, or if no traits have been applied, it returns C<undef>.
+This returns an array reference of all the traits which were applied
+to this attribute. If none were applied, this returns C<undef>.
-=item B<has_applied_traits>
+=item B<< $attr->has_applied_traits >>
-Returns true if this meta-attribute has any traits applied.
+Returns true if this attribute has any traits applied.
=back
=head1 COPYRIGHT AND LICENSE
-Copyright 2006-2008 by Infinity Interactive, Inc.
+Copyright 2006-2009 by Infinity Interactive, Inc.
L<http://www.iinteractive.com>
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