package Class::MOP::Immutable;
+use strict;
+use warnings;
+
+use Class::MOP::Method::Constructor;
+
+use Carp 'confess';
+use Scalar::Util 'blessed';
+
+our $VERSION = '0.78_02';
+$VERSION = eval $VERSION;
+our $AUTHORITY = 'cpan:STEVAN';
+
+use base 'Class::MOP::Object';
+
+sub new {
+ my ($class, @args) = @_;
+
+ unshift @args, 'metaclass' if @args % 2 == 1;
+
+ my %options = (
+ inline_accessors => 1,
+ inline_constructor => 1,
+ inline_destructor => 0,
+ constructor_name => 'new',
+ constructor_class => 'Class::MOP::Method::Constructor',
+ debug => 0,
+ @args,
+ );
+
+ my $self = $class->_new(
+ 'metaclass' => delete $options{metaclass},
+ 'options' => \%options,
+ 'immutable_metaclass' => undef,
+ 'inlined_constructor' => undef,
+ );
+
+ return $self;
+}
+
+sub _new {
+ my $class = shift;
+ my $options = @_ == 1 ? $_[0] : {@_};
+
+ bless $options, $class;
+}
+
+sub immutable_metaclass {
+ my $self = shift;
+
+ return $self->{'immutable_metaclass'} ||= $self->_create_immutable_metaclass;
+}
+
+sub metaclass { (shift)->{'metaclass'} }
+sub options { (shift)->{'options'} }
+sub inlined_constructor { (shift)->{'inlined_constructor'} }
+
+sub _create_immutable_metaclass {
+ my $self = shift;
+
+ # NOTE: The immutable version of the metaclass is just a
+ # anon-class which shadows the methods appropriately
+ return Class::MOP::Class->create_anon_class(
+ superclasses => [ blessed($self->metaclass) ],
+ methods => $self->_create_methods_for_immutable_metaclass,
+ );
+}
+
+sub make_metaclass_immutable {
+ my $self = shift;
+
+ $self->_inline_accessors;
+ $self->_inline_constructor;
+ $self->_inline_destructor;
+ $self->_check_memoized_methods;
+
+ my $metaclass = $self->metaclass;
+
+ $metaclass->{'___original_class'} = blessed($metaclass);
+ bless $metaclass => $self->immutable_metaclass->name;
+}
+
+sub _inline_accessors {
+ my $self = shift;
+
+ return unless $self->options->{inline_accessors};
+
+ foreach my $attr_name ( $self->metaclass->get_attribute_list ) {
+ $self->metaclass->get_attribute($attr_name)->install_accessors(1);
+ }
+}
+
+sub _inline_constructor {
+ my $self = shift;
+
+ return unless $self->options->{inline_constructor};
+
+ return
+ unless $self->options->{replace_constructor}
+ or !$self->metaclass->has_method(
+ $self->options->{constructor_name}
+ );
+
+ my $constructor_class = $self->options->{constructor_class};
+
+ my $constructor = $constructor_class->new(
+ options => $self->options,
+ metaclass => $self->metaclass,
+ is_inline => 1,
+ package_name => $self->metaclass->name,
+ name => $self->options->{constructor_name},
+ );
+
+ if ( $self->options->{replace_constructor}
+ or $constructor->can_be_inlined ) {
+ $self->metaclass->add_method(
+ $self->options->{constructor_name} => $constructor );
+ $self->{inlined_constructor} = $constructor;
+ }
+}
+
+sub _inline_destructor {
+ my $self = shift;
+
+ return unless $self->options->{inline_destructor};
+
+ ( exists $self->options->{destructor_class} )
+ || confess "The 'inline_destructor' option is present, but "
+ . "no destructor class was specified";
+
+ my $destructor_class = $self->options->{destructor_class};
+
+ return unless $destructor_class->is_needed( $self->metaclass );
+
+ my $destructor = $destructor_class->new(
+ options => $self->options,
+ metaclass => $self->metaclass,
+ package_name => $self->metaclass->name,
+ name => 'DESTROY'
+ );
+
+ $self->metaclass->add_method( 'DESTROY' => $destructor );
+}
+
+sub _check_memoized_methods {
+ my $self = shift;
+
+ my $memoized_methods = $self->options->{memoize};
+ foreach my $method_name ( keys %{$memoized_methods} ) {
+ my $type = $memoized_methods->{$method_name};
+
+ ( $self->metaclass->can($method_name) )
+ || confess "Could not find the method '$method_name' in "
+ . $self->metaclass->name;
+ }
+}
+my %DEFAULT_METHODS = (
+ # I don't really understand this, but removing it breaks tests (groditi)
+ meta => sub {
+ my $self = shift;
+ # if it is not blessed, then someone is asking
+ # for the meta of Class::MOP::Immutable
+ return Class::MOP::Class->initialize($self) unless blessed($self);
+ # otherwise, they are asking for the metaclass
+ # which has been made immutable, which is itself
+ # except in the cases where it is a metaclass itself
+ # that has been made immutable and for that we need
+ # to dig a bit ...
+ if ($self->isa('Class::MOP::Class')) {
+ return $self->{'___original_class'}->meta;
+ }
+ else {
+ return $self;
+ }
+ },
+ is_mutable => sub { 0 },
+ is_immutable => sub { 1 },
+ make_immutable => sub { () },
+);
+
+sub _create_methods_for_immutable_metaclass {
+ my $self = shift;
+
+ my $metaclass = $self->metaclass;
+ my $meta = $metaclass->meta;
+
+ return {
+ %DEFAULT_METHODS,
+ $self->_make_read_only_methods,
+ $self->_make_uncallable_methods,
+ $self->_make_memoized_methods,
+ $self->_make_wrapped_methods,
+ get_mutable_metaclass_name => sub { (shift)->{'___original_class'} },
+ immutable_transformer => sub {$self},
+ };
+}
+
+sub _make_read_only_methods {
+ my $self = shift;
+
+ my $metameta = $self->metaclass->meta;
+
+ my %methods;
+ foreach my $read_only_method ( @{ $self->options->{read_only} } ) {
+ my $method = $metameta->find_method_by_name($read_only_method);
+
+ ( defined $method )
+ || confess "Could not find the method '$read_only_method' in "
+ . $self->metaclass->name;
+
+ $methods{$read_only_method} = sub {
+ confess "This method is read-only" if scalar @_ > 1;
+ goto &{ $method->body };
+ };
+ }
+
+ return %methods;
+}
+
+sub _make_uncallable_methods {
+ my $self = shift;
+
+ my %methods;
+ foreach my $cannot_call_method ( @{ $self->options->{cannot_call} } ) {
+ $methods{$cannot_call_method} = sub {
+ confess
+ "This method ($cannot_call_method) cannot be called on an immutable instance";
+ };
+ }
+
+ return %methods;
+}
+
+sub _make_memoized_methods {
+ my $self = shift;
+
+ my %methods;
+
+ my $metameta = $self->metaclass->meta;
+
+ my $memoized_methods = $self->options->{memoize};
+ foreach my $method_name ( keys %{$memoized_methods} ) {
+ my $type = $memoized_methods->{$method_name};
+ my $key = '___' . $method_name;
+ my $method = $metameta->find_method_by_name($method_name);
+
+ if ( $type eq 'ARRAY' ) {
+ $methods{$method_name} = sub {
+ @{ $_[0]->{$key} } = $method->execute( $_[0] )
+ if !exists $_[0]->{$key};
+ return @{ $_[0]->{$key} };
+ };
+ }
+ elsif ( $type eq 'HASH' ) {
+ $methods{$method_name} = sub {
+ %{ $_[0]->{$key} } = $method->execute( $_[0] )
+ if !exists $_[0]->{$key};
+ return %{ $_[0]->{$key} };
+ };
+ }
+ elsif ( $type eq 'SCALAR' ) {
+ $methods{$method_name} = sub {
+ $_[0]->{$key} = $method->execute( $_[0] )
+ if !exists $_[0]->{$key};
+ return $_[0]->{$key};
+ };
+ }
+ }
+
+ return %methods;
+}
+
+sub _make_wrapped_methods {
+ my $self = shift;
+
+ my %methods;
+
+ my $wrapped_methods = $self->options->{wrapped};
+
+ my $metameta = $self->metaclass->meta;
+
+ foreach my $method_name ( keys %{$wrapped_methods} ) {
+ my $method = $metameta->find_method_by_name($method_name);
+
+ ( defined $method )
+ || confess "Could not find the method '$method_name' in "
+ . $self->metaclass->name;
+
+ my $wrapper = $wrapped_methods->{$method_name};
+
+ $methods{$method_name} = sub { $wrapper->( $method, @_ ) };
+ }
+
+ return %methods;
+}
+
+sub make_metaclass_mutable {
+ my $self = shift;
+
+ my $metaclass = $self->metaclass;
+
+ my $original_class = $metaclass->get_mutable_metaclass_name;
+ delete $metaclass->{'___original_class'};
+ bless $metaclass => $original_class;
+
+ my $memoized_methods = $self->options->{memoize};
+ foreach my $method_name ( keys %{$memoized_methods} ) {
+ my $type = $memoized_methods->{$method_name};
+
+ ( $metaclass->can($method_name) )
+ || confess "Could not find the method '$method_name' in "
+ . $metaclass->name;
+ if ( $type eq 'SCALAR' || $type eq 'ARRAY' || $type eq 'HASH' ) {
+ delete $metaclass->{ '___' . $method_name };
+ }
+ }
+
+ if ( $self->options->{inline_destructor}
+ && $metaclass->has_method('DESTROY') ) {
+ $metaclass->remove_method('DESTROY')
+ if blessed( $metaclass->get_method('DESTROY') ) eq
+ $self->options->{destructor_class};
+ }
+
+ # NOTE:
+ # 14:01 <@stevan> nah,. you shouldnt
+ # 14:01 <@stevan> they are just inlined
+ # 14:01 <@stevan> which is the default in Moose anyway
+ # 14:02 <@stevan> and adding new attributes will just DWIM
+ # 14:02 <@stevan> and you really cant change an attribute anyway
+ # if ($options{inline_accessors}) {
+ # foreach my $attr_name ($immutable->get_attribute_list) {
+ # my $attr = $immutable->get_attribute($attr_name);
+ # $attr->remove_accessors;
+ # $attr->install_accessors(0);
+ # }
+ # }
+
+ # 14:26 <@stevan> the only user of ::Method::Constructor is immutable
+ # 14:27 <@stevan> if someone uses it outside of immutable,.. they are either: mst or groditi
+ # 14:27 <@stevan> so I am not worried
+ if ( $self->options->{inline_constructor}
+ && $metaclass->has_method( $self->options->{constructor_name} ) ) {
+ my $constructor_class = $self->options->{constructor_class}
+ || 'Class::MOP::Method::Constructor';
+
+ if (
+ blessed(
+ $metaclass->get_method( $self->options->{constructor_name} )
+ ) eq $constructor_class
+ ) {
+ $metaclass->remove_method( $self->options->{constructor_name} );
+ $self->{inlined_constructor} = undef;
+ }
+ }
+}
+
1;
__END__
=pod
-Okay, so here is the basic idea.
-
-First, your metaclass must register with Class::MOP::Immutable
-at which point an anon-class is created which will be the
-immutable class which your metaclass will be blessed into.
-
-This allows immutable versions of any metaclass to be created
-on the fly if needed.
-
-NOTE:
-Remember the immutable version of the metaclass will be used to
-construct/convert mutable instances into immutable versions. So
-it itself is a metaclass.
-
- Class::MOP::Immutable->make_immutable_metaclass(
- # name of the metaclass we are
- # making immutable
- metaclass => 'Class::MOP::Class',
-
- # names of some method metaclasses
- # which will be useful in the creation
- # of the immutable versions
- constructor_class => 'Class::MOP::Method::Constructor',
- accessor_class => 'Class::MOP::Method::Accessor', # ?? maybe
-
- # options which the immutable converter
- # will accept, not exactly sure about
- # this one,.. it might have to be hard
- # coded in some way.
- available_options => [qw[
- inline_accessors
- inline_constructor
- constructor_name
- ]],
-
- # multiple lists of things which can
- # be done to the metaclass ..
-
- # make these methods die when called
- disallow => [qw[
- add_method
- alias_method
- remove_method
- add_attribute
- remove_attribute
- add_package_symbol
- remove_package_symbol
- ]],
-
- # memoize the value of these methods
- memoize => [qw[
- class_precedence_list
- compute_all_applicable_attributes
- get_meta_instance
- get_method_map
- ]],
-
- # make these methods read only
- readonly => [qw[
- superclasses
- ]],
- );
-
-Now, this will work just fine for singular metas, but
-we want this to be able to work for extensions to the
-metaclasses as well.
-
-Here is how we do that:
-
- Class::MOP::Immutable->make_immutable_metaclass(
- # the metaclass name ...
- metaclass => 'Moose::Meta::Class',
-
- # inherit the options from immutable
- # parent class (Class::MOP::Class)
- inherit => 1
-
- constructor_class => 'Moose::Method::Constructor',
- accessor_class => 'Moose::Method::Accessor', # ?? maybe
-
- disallow => [qw[
- add_roles
- ...
- ]],
-
- memoize => [qw[
- roles
- ...
- ]]
- );
-
-When you specify C<inherit => 1> you are telling
-Class::MOP::Immutable that you want to inherit your
-parents options. This means that you get all their
-and yours (perhaps some basic conflict resolution
-can be added here as well).
-
-It might make sense to also allow a more granular
-approach such as:
-
- inherit => {
- disallow => 'merge',
- memoize => 'override',
- readonly => 'ignore',
- }
-
-which would allow you to specify in more detail how
-you would like to handle each change. This might be
-more than anyone ever needs so we can probably hold
-off for now.
-
-Ultimately it will be the responsibility of the
-author to make sure their immutable options make sense.
-
-The reason I say this is that you could easily get
-carried away in the number of items you choose to
-memoize or such. This would not make a lot of sense,
-it would make more sense to memoize at the "topmost"
-level instead, rather than all the intermediate ones.
-
-It's basically gonna be a trade off.
+=head1 NAME
-=cut
+Class::MOP::Immutable - A class to transform Class::MOP::Class metaclasses
+
+=head1 SYNOPSIS
+
+ use Class::MOP::Immutable;
+
+ my $immutable_metaclass = Class::MOP::Immutable->new($metaclass, {
+ read_only => [qw/superclasses/],
+ cannot_call => [qw/
+ add_method
+ alias_method
+ remove_method
+ add_attribute
+ remove_attribute
+ add_package_symbol
+ remove_package_symbol
+ /],
+ memoize => {
+ class_precedence_list => 'ARRAY',
+ compute_all_applicable_attributes => 'ARRAY',
+ get_meta_instance => 'SCALAR',
+ get_method_map => 'SCALAR',
+ }
+ });
+
+ $immutable_metaclass->make_metaclass_immutable;
+
+=head1 DESCRIPTION
+
+This class encapsulates the logic behind immutabilization.
+
+This class provides generic immutabilization logic. Decisions about
+I<what> gets transformed are up to the caller.
+
+Immutabilization allows for a number of transformations. It can ask
+the calling metaclass to inline methods such as the constructor,
+destructor, or accessors. It can memoize metaclass accessors
+themselves. It can also turn read-write accessors in the metaclass
+into read-only methods, and make attempting to set these values an
+error. Finally, it can make some methods throw an exception when they
+are called. This is used to disable methods that can alter the class.
+
+=head1 METHODS
+
+=over 4
+
+=item B<< Class::MOP::Immutable->new($metaclass, %options) >>
+
+This method takes a metaclass object (typically a L<Class::MOP::Class>
+object) and a hash of options.
+
+It returns a new transformer, but does not actually do any
+transforming yet.
+
+This method accepts the following options:
+
+=over 8
+
+=item * inline_accessors
+
+=item * inline_constructor
+
+=item * inline_destructor
+
+These are all booleans indicating whether the specified method(s)
+should be inlined.
+
+By default, accessors and the constructor are inlined, but not the
+destructor.
+
+=item * replace_constructor
+
+This is a boolean indicating whether an existing constructor should be
+replaced when inlining a constructor. This defaults to false.
+
+=item * constructor_name
+
+This is the constructor method name. This defaults to "new".
+=item * constructor_class
+
+The name of the method metaclass for constructors. It will be used to
+generate the inlined constructor. This defaults to
+"Class::MOP::Method::Constructor".
+
+=item * destructor_class
+
+The name of the method metaclass for destructors. It will be used to
+generate the inlined destructor. This defaults to
+"Class::MOP::Method::Denstructor".
+
+=item * memoize
+
+This option takes a hash reference. They keys are method names to be
+memoized, and the values are the type of data the method returns. This
+can be one of "SCALAR", "ARRAY", or "HASH".
+
+=item * read_only
+
+This option takes an array reference of read-write methods which will
+be made read-only. After they are transformed, attempting to set them
+will throw an error.
+
+=item * cannot_call
+
+This option takes an array reference of methods which cannot be called
+after immutabilization. Attempting to call these methods will throw an
+error.
+
+=item * wrapped
+
+This option takes a hash reference. The keys are method names and the
+body is a subroutine reference which will wrap the named method. This
+allows you to do some sort of custom transformation to a method.
+
+=back
+
+=item B<< $transformer->options >>
+
+Returns a hash reference of the options passed to C<new>.
+
+=item B<< $transformer->metaclass >>
+
+Returns the metaclass object passed to C<new>.
+
+=item B<< $transformer->immutable_metaclass >>
+
+Returns the immutable metaclass object that is created by the
+transformation process.
+
+=item B<< $transformer->inlined_constructor >>
+
+If the constructor was inlined, this returns the constructor method
+object that was created to do this.
+
+=item B<< $transformer->make_metaclass_immutable >>
+
+Makes the transformer's metaclass immutable.
+
+=item B<< $transformer->make_metaclass_mutable >>
+
+Makes the transformer's metaclass mutable.
+
+=back
+
+=head1 AUTHORS
+
+Stevan Little E<lt>stevan@iinteractive.comE<gt>
+
+=head1 COPYRIGHT AND LICENSE
+
+Copyright 2006-2009 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
projects / gitmo/Class-MOP.git / blobdiff