use strict;
use warnings;
-our $VERSION = '0.39';
+use 5.008;
+
+our $VERSION = '0.58';
+$VERSION = eval $VERSION;
our $AUTHORITY = 'cpan:STEVAN';
-use Scalar::Util 'blessed', 'reftype';
-use Carp 'confess';
-use Sub::Name 'subname';
+use Scalar::Util 'blessed';
+use Carp 'confess', 'croak', 'cluck';
-use Sub::Exporter;
+use Moose::Exporter;
-use Class::MOP 0.51;
+use Class::MOP 0.67;
use Moose::Meta::Class;
use Moose::Meta::TypeConstraint;
-use Moose::Meta::TypeConstraint::Class;
use Moose::Meta::TypeCoercion;
use Moose::Meta::Attribute;
use Moose::Meta::Instance;
+use Moose::Object;
+
use Moose::Meta::Role;
+use Moose::Meta::Role::Composite;
+use Moose::Meta::Role::Application;
+use Moose::Meta::Role::Application::RoleSummation;
+use Moose::Meta::Role::Application::ToClass;
+use Moose::Meta::Role::Application::ToRole;
+use Moose::Meta::Role::Application::ToInstance;
-use Moose::Object;
use Moose::Util::TypeConstraints;
use Moose::Util ();
-{
- my $CALLER;
-
- sub init_meta {
- my ( $class, $base_class, $metaclass ) = @_;
- $base_class = 'Moose::Object' unless defined $base_class;
- $metaclass = 'Moose::Meta::Class' unless defined $metaclass;
-
- confess
- "The Metaclass $metaclass must be a subclass of Moose::Meta::Class."
- unless $metaclass->isa('Moose::Meta::Class');
-
- # make a subtype for each Moose class
- class_type($class)
- unless find_type_constraint($class);
-
- my $meta;
- if ( $class->can('meta') ) {
- # NOTE:
- # this is the case where the metaclass pragma
- # was used before the 'use Moose' statement to
- # override a specific class
- $meta = $class->meta();
- ( blessed($meta) && $meta->isa('Moose::Meta::Class') )
- || confess "You already have a &meta function, but it does not return a Moose::Meta::Class";
- }
- else {
- # NOTE:
- # this is broken currently, we actually need
- # to allow the possiblity of an inherited
- # meta, which will not be visible until the
- # user 'extends' first. This needs to have
- # more intelligence to it
- $meta = $metaclass->initialize($class);
- $meta->add_method(
- 'meta' => sub {
- # re-initialize so it inherits properly
- $metaclass->initialize( blessed( $_[0] ) || $_[0] );
- }
- );
- }
+sub throw_error {
+ # FIXME This
+ shift;
+ goto \&confess
+}
- # make sure they inherit from Moose::Object
- $meta->superclasses($base_class)
- unless $meta->superclasses();
-
- return $meta;
- }
+sub extends {
+ my $class = shift;
- my %exports = (
- extends => sub {
- my $class = $CALLER;
- return subname 'Moose::extends' => sub (@) {
- confess "Must derive at least one class" unless @_;
-
- my @supers = @_;
- foreach my $super (@supers) {
- Class::MOP::load_class($super);
- }
+ croak "Must derive at least one class" unless @_;
- # this checks the metaclass to make sure
- # it is correct, sometimes it can get out
- # of sync when the classes are being built
- my $meta = $class->meta->_fix_metaclass_incompatability(@supers);
- $meta->superclasses(@supers);
- };
- },
- with => sub {
- my $class = $CALLER;
- return subname 'Moose::with' => sub (@) {
- Moose::Util::apply_all_roles($class->meta, @_)
- };
- },
- has => sub {
- my $class = $CALLER;
- return subname 'Moose::has' => sub ($;%) {
- my $name = shift;
- die 'Usage: has \'name\' => ( key => value, ... )' if @_ == 1;
- my %options = @_;
- my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
- $class->meta->add_attribute( $_, %options ) for @$attrs;
- };
- },
- before => sub {
- my $class = $CALLER;
- return subname 'Moose::before' => sub (@&) {
- my $code = pop @_;
- my $meta = $class->meta;
- $meta->add_before_method_modifier( $_, $code ) for @_;
- };
- },
- after => sub {
- my $class = $CALLER;
- return subname 'Moose::after' => sub (@&) {
- my $code = pop @_;
- my $meta = $class->meta;
- $meta->add_after_method_modifier( $_, $code ) for @_;
- };
- },
- around => sub {
- my $class = $CALLER;
- return subname 'Moose::around' => sub (@&) {
- my $code = pop @_;
- my $meta = $class->meta;
- $meta->add_around_method_modifier( $_, $code ) for @_;
- };
- },
- super => sub {
- {
- our %SUPER_SLOT;
- no strict 'refs';
- $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
- }
- return subname 'Moose::super' => sub { };
- },
- override => sub {
- my $class = $CALLER;
- return subname 'Moose::override' => sub ($&) {
- my ( $name, $method ) = @_;
- $class->meta->add_override_method_modifier( $name => $method );
- };
- },
- inner => sub {
- {
- our %INNER_SLOT;
- no strict 'refs';
- $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
- }
- return subname 'Moose::inner' => sub { };
- },
- augment => sub {
- my $class = $CALLER;
- return subname 'Moose::augment' => sub (@&) {
- my ( $name, $method ) = @_;
- $class->meta->add_augment_method_modifier( $name => $method );
- };
- },
- make_immutable => sub {
- my $class = $CALLER;
- return subname 'Moose::make_immutable' => sub {
- $class->meta->make_immutable(@_);
- };
- },
- confess => sub {
- return \&Carp::confess;
- },
- blessed => sub {
- return \&Scalar::Util::blessed;
- },
- );
-
- my $exporter = Sub::Exporter::build_exporter(
- {
- exports => \%exports,
- groups => { default => [':all'] }
- }
- );
-
- # 1 extra level because it's called by import so there's a layer of indirection
- sub _get_caller{
- my $offset = 1;
- return
- ref $_[1] && defined $_[1]->{into}
- ? $_[1]->{into}
- : ref $_[1] && defined $_[1]->{into_level}
- ? caller($offset + $_[1]->{into_level})
- : caller($offset);
+ my @supers = @_;
+ foreach my $super (@supers) {
+ Class::MOP::load_class($super);
+ croak "You cannot inherit from a Moose Role ($super)"
+ if $super->can('meta') &&
+ blessed $super->meta &&
+ $super->meta->isa('Moose::Meta::Role')
}
- sub import {
- $CALLER = _get_caller(@_);
- # this works because both pragmas set $^H (see perldoc perlvar)
- # which affects the current compilation - i.e. the file who use'd
- # us - which is why we don't need to do anything special to make
- # it affect that file rather than this one (which is already compiled)
- strict->import;
- warnings->import;
+ # this checks the metaclass to make sure
+ # it is correct, sometimes it can get out
+ # of sync when the classes are being built
+ my $meta = Moose::Meta::Class->initialize($class);
+ $meta->superclasses(@supers);
+}
+
+sub with {
+ my $class = shift;
+ Moose::Util::apply_all_roles(Class::MOP::Class->initialize($class), @_);
+}
- # we should never export to main
- return if $CALLER eq 'main';
+sub has {
+ my $class = shift;
+ my $name = shift;
+ croak 'Usage: has \'name\' => ( key => value, ... )' if @_ == 1;
+ my %options = @_;
+ my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
+ Class::MOP::Class->initialize($class)->add_attribute( $_, %options ) for @$attrs;
+}
- init_meta( $CALLER, 'Moose::Object' );
+sub before {
+ my $class = shift;
+ Moose::Util::add_method_modifier($class, 'before', \@_);
+}
+
+sub after {
+ my $class = shift;
+ Moose::Util::add_method_modifier($class, 'after', \@_);
+}
+
+sub around {
+ my $class = shift;
+ Moose::Util::add_method_modifier($class, 'around', \@_);
+}
- goto $exporter;
+sub super {
+ return unless our $SUPER_BODY; $SUPER_BODY->(our @SUPER_ARGS);
+}
+
+sub override {
+ my $class = shift;
+ my ( $name, $method ) = @_;
+ Class::MOP::Class->initialize($class)->add_override_method_modifier( $name => $method );
+}
+
+sub inner {
+ my $pkg = caller();
+ our ( %INNER_BODY, %INNER_ARGS );
+
+ if ( my $body = $INNER_BODY{$pkg} ) {
+ my @args = @{ $INNER_ARGS{$pkg} };
+ local $INNER_ARGS{$pkg};
+ local $INNER_BODY{$pkg};
+ return $body->(@args);
+ } else {
+ return;
+ }
+}
+
+sub augment {
+ my $class = shift;
+ my ( $name, $method ) = @_;
+ Class::MOP::Class->initialize($class)->add_augment_method_modifier( $name => $method );
+}
+
+sub make_immutable {
+ my $class = shift;
+ cluck "The make_immutable keyword has been deprecated, " .
+ "please go back to __PACKAGE__->meta->make_immutable\n";
+ Class::MOP::Class->initialize($class)->make_immutable(@_);
+}
+
+Moose::Exporter->setup_import_methods(
+ with_caller => [
+ qw( extends with has before after around override augment make_immutable )
+ ],
+ as_is => [
+ qw( super inner ),
+ \&Carp::confess,
+ \&Scalar::Util::blessed,
+ ],
+);
+
+sub init_meta {
+ # This used to be called as a function. This hack preserves
+ # backwards compatibility.
+ if ( $_[0] ne __PACKAGE__ ) {
+ return __PACKAGE__->init_meta(
+ for_class => $_[0],
+ base_class => $_[1],
+ metaclass => $_[2],
+ );
}
- sub unimport {
- no strict 'refs';
- my $class = _get_caller(@_);
+ shift;
+ my %args = @_;
- # loop through the exports ...
- foreach my $name ( keys %exports ) {
+ my $class = $args{for_class}
+ or Moose->throw_error("Cannot call init_meta without specifying a for_class");
+ my $base_class = $args{base_class} || 'Moose::Object';
+ my $metaclass = $args{metaclass} || 'Moose::Meta::Class';
- # if we find one ...
- if ( defined &{ $class . '::' . $name } ) {
- my $keyword = \&{ $class . '::' . $name };
+ Moose->throw_error("The Metaclass $metaclass must be a subclass of Moose::Meta::Class.")
+ unless $metaclass->isa('Moose::Meta::Class');
- # make sure it is from Moose
- my ($pkg_name) = Class::MOP::get_code_info($keyword);
- next if $@;
- next if $pkg_name ne 'Moose';
+ # make a subtype for each Moose class
+ class_type($class)
+ unless find_type_constraint($class);
- # and if it is from Moose then undef the slot
- delete ${ $class . '::' }{$name};
+ my $meta;
+
+ if ( $meta = Class::MOP::get_metaclass_by_name($class) ) {
+ unless ( $meta->isa("Moose::Meta::Class") ) {
+ Moose->throw_error("$class already has a metaclass, but it does not inherit $metaclass ($meta)");
+ }
+ } else {
+ # no metaclass, no 'meta' method
+
+ # now we check whether our ancestors have metaclass, and if so borrow that
+ my ( undef, @isa ) = @{ $class->mro::get_linear_isa };
+
+ foreach my $ancestor ( @isa ) {
+ my $ancestor_meta = Class::MOP::get_metaclass_by_name($ancestor) || next;
+
+ my $ancestor_meta_class = ($ancestor_meta->is_immutable
+ ? $ancestor_meta->get_mutable_metaclass_name
+ : ref($ancestor_meta));
+
+ # if we have an ancestor metaclass that inherits $metaclass, we use
+ # that. This is like _fix_metaclass_incompatibility, but we can do it now.
+
+ # the case of having an ancestry is not very common, but arises in
+ # e.g. Reaction
+ unless ( $metaclass->isa( $ancestor_meta_class ) ) {
+ if ( $ancestor_meta_class->isa($metaclass) ) {
+ $metaclass = $ancestor_meta_class;
+ }
}
}
+
+ $meta = $metaclass->initialize($class);
+ }
+
+ if ( $class->can('meta') ) {
+ # check 'meta' method
+
+ # it may be inherited
+
+ # NOTE:
+ # this is the case where the metaclass pragma
+ # was used before the 'use Moose' statement to
+ # override a specific class
+ my $method_meta = $class->meta;
+
+ ( blessed($method_meta) && $method_meta->isa('Moose::Meta::Class') )
+ || Moose->throw_error("$class already has a &meta function, but it does not return a Moose::Meta::Class ($meta)");
+
+ $meta = $method_meta;
}
+ unless ( $meta->has_method("meta") ) { # don't overwrite
+ # also check for inherited non moose 'meta' method?
+ # FIXME also skip this if the user requested by passing an option
+ $meta->add_method(
+ 'meta' => sub {
+ # re-initialize so it inherits properly
+ $metaclass->initialize( ref($_[0]) || $_[0] );
+ }
+ );
+ }
+
+ # make sure they inherit from Moose::Object
+ $meta->superclasses($base_class)
+ unless $meta->superclasses();
+
+ return $meta;
+}
+
+# This may be used in some older MooseX extensions.
+sub _get_caller {
+ goto &Moose::Exporter::_get_caller;
}
## make 'em all immutable
$_->meta->make_immutable(
- inline_constructor => 0,
+ inline_constructor => 1,
+ constructor_name => "_new",
inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
)
- for (
- 'Moose::Meta::Attribute',
- 'Moose::Meta::Class',
- 'Moose::Meta::Instance',
-
- 'Moose::Meta::TypeConstraint',
- 'Moose::Meta::TypeConstraint::Union',
- 'Moose::Meta::TypeConstraint::Parameterized',
- 'Moose::Meta::TypeCoercion',
-
- 'Moose::Meta::Method',
- 'Moose::Meta::Method::Accessor',
- 'Moose::Meta::Method::Constructor',
- 'Moose::Meta::Method::Destructor',
- 'Moose::Meta::Method::Overriden',
-
- 'Moose::Meta::Role',
- 'Moose::Meta::Role::Method',
- 'Moose::Meta::Role::Method::Required',
- );
+ for (qw(
+ Moose::Meta::Attribute
+ Moose::Meta::Class
+ Moose::Meta::Instance
+
+ Moose::Meta::TypeConstraint
+ Moose::Meta::TypeConstraint::Union
+ Moose::Meta::TypeConstraint::Parameterized
+ Moose::Meta::TypeConstraint::Parameterizable
+ Moose::Meta::TypeConstraint::Enum
+ Moose::Meta::TypeConstraint::Class
+ Moose::Meta::TypeConstraint::Role
+ Moose::Meta::TypeConstraint::Registry
+ Moose::Meta::TypeCoercion
+ Moose::Meta::TypeCoercion::Union
+
+ Moose::Meta::Method
+ Moose::Meta::Method::Accessor
+ Moose::Meta::Method::Constructor
+ Moose::Meta::Method::Destructor
+ Moose::Meta::Method::Overriden
+ Moose::Meta::Method::Augmented
+
+ Moose::Meta::Role
+ Moose::Meta::Role::Method
+ Moose::Meta::Role::Method::Required
+
+ Moose::Meta::Role::Composite
+
+ Moose::Meta::Role::Application
+ Moose::Meta::Role::Application::RoleSummation
+ Moose::Meta::Role::Application::ToClass
+ Moose::Meta::Role::Application::ToRole
+ Moose::Meta::Role::Application::ToInstance
+));
1;
Moose is an extension of the Perl 5 object system.
-=head2 Another object system!?!?
-
-Yes, I know there has been an explosion recently of new ways to
-build object's in Perl 5, most of them based on inside-out objects
-and other such things. Moose is different because it is not a new
-object system for Perl 5, but instead an extension of the existing
-object system.
-
-Moose is built on top of L<Class::MOP>, which is a metaclass system
-for Perl 5. This means that Moose not only makes building normal
-Perl 5 objects better, but it also provides the power of metaclass
-programming.
-
-=head2 Is this for real? Or is this just an experiment?
-
-Moose is I<based> on the prototypes and experiments I did for the Perl 6
-meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
-
-=head2 Is this ready for use in production?
+The main goal of Moose is to make Perl 5 Object Oriented programming
+easier, more consistent and less tedious. With Moose you can to think
+more about what you want to do and less about the mechanics of OOP.
-Yes, I believe that it is.
+Additionally, Moose is built on top of L<Class::MOP>, which is a
+metaclass system for Perl 5. This means that Moose not only makes
+building normal Perl 5 objects better, but it provides the power of
+metaclass programming as well.
-Moose has been used successfully in production environemnts by several people
-and companies (including the one I work for). There are Moose applications
-which have been in production with little or no issue now for well over a year.
-I consider it highly stable and we are commited to keeping it stable.
+=head2 New to Moose?
-Of course, in the end, you need to make this call yourself. If you have
-any questions or concerns, please feel free to email me, or even the list
-or just stop by #moose and ask away.
+If you're new to Moose, the best place to start is the L<Moose::Intro>
+docs, followed by the L<Moose::Cookbook>. The intro will show you what
+Moose is, and how it makes Perl 5 OO better.
-=head2 Is Moose just Perl 6 in Perl 5?
-
-No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
-Instead, it is an OO system for Perl 5. I built Moose because I was tired of
-writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
-instead of switching to Ruby, I wrote Moose :)
-
-=head2 Wait, I<post> modern, I thought it was just I<modern>?
-
-So I was reading Larry Wall's talk from the 1999 Linux World entitled
-"Perl, the first postmodern computer language" in which he talks about how
-he picked the features for Perl because he thought they were cool and he
-threw out the ones that he thought sucked. This got me thinking about how
-we have done the same thing in Moose. For Moose, we have "borrowed" features
-from Perl 6, CLOS (LISP), Smalltalk, Java, BETA, OCaml, Ruby and more, and
-the bits we didn't like (cause they sucked) we tossed aside. So for this
-reason (and a few others) I have re-dubbed Moose a I<postmodern> object system.
-
-Nuff Said.
+The cookbook recipes on Moose basics will get you up to speed with
+many of Moose's features quickly. Once you have an idea of what Moose
+can do, you can use the API documentation to get more detail on
+features which interest you.
=head2 Moose Extensions
-The L<MooseX::> namespace is the official place to find Moose extensions.
-There are a number of these modules out on CPAN right now the best way to
-find them is to search for MooseX:: on search.cpan.org.
+The C<MooseX::> namespace is the official place to find Moose extensions.
+These extensions can be found on the CPAN. The easiest way to find them
+is to search for them (L<http://search.cpan.org/search?query=MooseX::>),
+or to examine L<Task::Moose> which aims to keep an up-to-date, easily
+installable list of Moose extensions.
=head1 BUILDING CLASSES WITH MOOSE
setting defaults where appropriate, and performing any type constraint checking
or coercion.
-=head1 EXPORTED FUNCTIONS
+=head1 PROVIDED METHODS
-Moose will export a number of functions into the class's namespace which
-may then be used to set up the class. These functions all work directly
-on the current class.
+Moose provides a number of methods to all your classes, mostly through the
+inheritance of L<Moose::Object>. There is however, one exception.
=over 4
This is a method which provides access to the current class's metaclass.
+=back
+
+=head1 EXPORTED FUNCTIONS
+
+Moose will export a number of functions into the class's namespace which
+may then be used to set up the class. These functions all work directly
+on the current class.
+
+=over 4
+
=item B<extends (@superclasses)>
This function will set the superclass(es) for the current class.
=item B<with (@roles)>
-This will apply a given set of C<@roles> to the local class. Role support
-is currently under heavy development; see L<Moose::Role> for more details.
+This will apply a given set of C<@roles> to the local class.
=item B<has $name =E<gt> %options>
only). These will create either a read/write accessor or a read-only
accessor respectively, using the same name as the C<$name> of the attribute.
-If you need more control over how your accessors are named, you can use the
-I<reader>, I<writer> and I<accessor> options inherited from
-L<Class::MOP::Attribute>.
+If you need more control over how your accessors are named, you can
+use the L<reader|Class::MOP::Attribute/reader>,
+L<writer|Class::MOP::Attribute/writer> and
+L<accessor|Class::MOP::Attribute/accessor> options inherited from
+L<Class::MOP::Attribute>, however if you use those, you won't need the
+I<is> option.
=item I<isa =E<gt> $type_name>
This will attempt to use coercion with the supplied type constraint to change
the value passed into any accessors or constructors. You B<must> have supplied
-a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
+a type constraint in order for this to work. See L<Moose::Cookbook::Basics::Recipe5>
for an example.
=item I<does =E<gt> $role_name>
This tells the accessor whether to automatically dereference the value returned.
This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
-=item I<metaclass =E<gt> $metaclass_name>
-
-This tells the class to use a custom attribute metaclass for this particular
-attribute. Custom attribute metaclasses are useful for extending the
-capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
-but they are still a fairly advanced topic and too much to cover here. I will
-try and write a recipe on them soon.
-
-The default behavior here is to just load C<$metaclass_name>; however, we also
-have a way to alias to a shorter name. This will first look to see if
-B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
-will then check to see if that has the method C<register_implementation>, which
-should return the actual name of the custom attribute metaclass. If there is no
-C<register_implementation> method, it will fall back to using
-B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
-
=item I<trigger =E<gt> $code>
The I<trigger> option is a CODE reference which will be called after the value of
the attribute is set. The CODE ref will be passed the instance itself, the
updated value and the attribute meta-object (this is for more advanced fiddling
and can typically be ignored). You B<cannot> have a trigger on a read-only
-attribute.
+attribute.
+
+B<NOTE:> Triggers will only fire when you B<assign> to the attribute,
+either in the constructor, or using the writer. Default and built values will
+B<not> cause the trigger to be fired.
=item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
This is a pretty complex and powerful option. It accepts many different option
formats, each with its own benefits and drawbacks.
-B<NOTE:> This feature is no longer experimental, but it may still have subtle
-bugs lurking in the deeper corners. If you think you have found a bug, you
-probably have, so please report it to me right away.
-
B<NOTE:> The class being delegated to does not need to be a Moose based class,
which is why this feature is especially useful when wrapping non-Moose classes.
in the class being delegated to.
This can be very useful for recursive classes like trees. Here is a
-quick example (soon to be expanded into a Moose::Cookbook::Recipe):
+quick example (soon to be expanded into a Moose::Cookbook recipe):
package Tree;
use Moose;
=back
+=item I<metaclass =E<gt> $metaclass_name>
+
+This tells the class to use a custom attribute metaclass for this particular
+attribute. Custom attribute metaclasses are useful for extending the
+capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
+but they are still a fairly advanced topic and too much to cover here, see
+L<Moose::Cookbook::Meta::Recipe1> for more information.
+
+The default behavior here is to just load C<$metaclass_name>; however, we also
+have a way to alias to a shorter name. This will first look to see if
+B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
+will then check to see if that has the method C<register_implementation>, which
+should return the actual name of the custom attribute metaclass. If there is no
+C<register_implementation> method, it will fall back to using
+B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
+
+=item I<traits =E<gt> [ @role_names ]>
+
+This tells Moose to take the list of C<@role_names> and apply them to the
+attribute meta-object. This is very similar to the I<metaclass> option, but
+allows you to use more than one extension at a time.
+
+See L<TRAIT NAME RESOLUTION> for details on how a trait name is
+resolved to a class name.
+
+Also see L<Moose::Cookbook::Meta::Recipe3> for a metaclass trait
+example.
+
+=item I<builder>
+
+The value of this key is the name of the method that will be called to
+obtain the value used to initialize the attribute. See the L<builder
+option docs in Class::MOP::Attribute|Class::MOP::Attribute/builder>
+for more information.
+
+=item I<default>
+
+The value of this key is the default value which will initialize the attribute.
+
+NOTE: If the value is a simple scalar (string or number), then it can
+be just passed as is. However, if you wish to initialize it with a
+HASH or ARRAY ref, then you need to wrap that inside a CODE reference.
+See the L<default option docs in
+Class::MOP::Attribute|Class::MOP::Attribute/default> for more
+information.
+
+=item I<initializer>
+
+This may be a method name (referring to a method on the class with
+this attribute) or a CODE ref. The initializer is used to set the
+attribute value on an instance when the attribute is set during
+instance initialization (but not when the value is being assigned
+to). See the L<initializer option docs in
+Class::MOP::Attribute|Class::MOP::Attribute/initializer> for more
+information.
+
+=item I<clearer>
+
+Allows you to clear the value, see the L<clearer option docs in
+Class::MOP::Attribute|Class::MOP::Attribute/clearer> for more
+information.
+
+=item I<predicate>
+
+Basic test to see if a value has been set in the attribute, see the
+L<predicate option docs in
+Class::MOP::Attribute|Class::MOP::Attribute/predicate> for more
+information.
+
=back
=item B<has +$name =E<gt> %options>
package Foo::Role;
use Moose::Role;
-
+
has 'message' => (
is => 'rw',
isa => 'Str',
default => 'Hello, I am a Foo'
);
-
+
package My::Foo;
use Moose;
-
+
with 'Foo::Role';
-
+
has '+message' => (default => 'Hello I am My::Foo');
In this case, we are basically taking the attribute which the role supplied
=item I<isa>
-You I<are> allowed to change the type, B<if and only if> the new type is a
-subtype of the old type.
+You I<are> allowed to change the type without restriction.
+
+It is recommended that you use this freedom with caution. We used to
+only allow for extension only if the type was a subtype of the parent's
+type, but we felt that was too restrictive and is better left as a
+policy descision.
=item I<handles>
You are allowed to B<add> a new C<builder> definition, but you are B<not>
allowed to I<change> one.
+=item I<metaclass>
+
+You are allowed to B<add> a new C<metaclass> definition, but you are
+B<not> allowed to I<change> one.
+
+=item I<traits>
+
+You are allowed to B<add> additional traits to the C<traits> definition.
+These traits will be composed into the attribute, but pre-existing traits
+B<are not> overridden, or removed.
+
=back
=item B<before $name|@names =E<gt> sub { ... }>
The keyword C<inner>, much like C<super>, is a no-op outside of the context of
an C<augment> method. You can think of C<inner> as being the inverse of
C<super>; the details of how C<inner> and C<augment> work is best described in
-the L<Moose::Cookbook>.
+the L<Moose::Cookbook::Basics::Recipe6>.
=item B<augment ($name, &sub)>
An C<augment> method, is a way of explicitly saying "I am augmenting this
method from my superclass". Once again, the details of how C<inner> and
-C<augment> work is best described in the L<Moose::Cookbook>.
+C<augment> work is best described in the L<Moose::Cookbook::Basics::Recipe6>.
=item B<confess>
This is the C<Carp::confess> function, and exported here because I use it
-all the time. This feature may change in the future, so you have been warned.
+all the time.
=item B<blessed>
=back
+=head1 METACLASS TRAITS
+
+When you use Moose, you can also specify traits which will be applied
+to your metaclass:
+
+ use Moose -traits => 'My::Trait';
+
+This is very similar to the attribute traits feature. When you do
+this, your class's C<meta> object will have the specified traits
+applied to it. See L<TRAIT NAME RESOLUTION> for more details.
+
+=head1 TRAIT NAME RESOLUTION
+
+By default, when given a trait name, Moose simply tries to load a
+class of the same name. If such a class does not exist, it then looks
+for for a class matching
+B<Moose::Meta::$type::Custom::Trait::$trait_name>. The C<$type>
+variable here will be one of B<Attribute> or B<Class>, depending on
+what the trait is being applied to.
+
+If a class with this long name exists, Moose checks to see if it has
+the method C<register_implementation>. This method is expected to
+return the I<real> class name of the trait. If there is no
+C<register_implementation> method, it will fall back to using
+B<Moose::Meta::$type::Custom::Trait::$trait> as the trait name.
+
+If all this is confusing, take a look at
+L<Moose::Cookbook::Meta::Recipe3>, which demonstrates how to create an
+attribute trait.
+
=head1 UNIMPORTING FUNCTIONS
=head2 B<unimport>
=head1 EXTENDING AND EMBEDDING MOOSE
-Moose also offers some options for extending or embedding it into your own
-framework. The basic premise is to have something that sets up your class'
-metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
-Here is an example:
+To learn more about extending Moose, we recommend checking out the
+"Extending" recipes in the L<Moose::Cookbook>, starting with
+L<Moose::Cookbook::Extending::Recipe1>, which provides an overview of
+all the different ways you might extend Moose.
- package MyFramework;
- use Moose;
-
- sub import {
- my $CALLER = caller();
+=head2 B<< Moose->init_meta(for_class => $class, base_class => $baseclass, metaclass => $metaclass) >>
- strict->import;
- warnings->import;
+The C<init_meta> method sets up the metaclass object for the class
+specified by C<for_class>. This method injects a a C<meta> accessor
+into the class so you can get at this object. It also sets the class's
+superclass to C<base_class>, with L<Moose::Object> as the default.
- # we should never export to main
- return if $CALLER eq 'main';
- Moose::init_meta( $CALLER, 'MyFramework::Base' );
- Moose->import({into => $CALLER});
+You can specify an alternate metaclass with the C<metaclass> parameter.
- # Do my custom framework stuff
+For more detail on this topic, see L<Moose::Cookbook::Extending::Recipe2>.
- return 1;
- }
+This method used to be documented as a function which accepted
+positional parameters. This calling style will still work for
+backwards compatibility, but is deprecated.
=head2 B<import>
Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
-and C<{into_level =E<gt> 1}>
+and C<{into_level =E<gt> 1}>.
+
+B<NOTE>: Doing this is more or less deprecated. Use L<Moose::Exporter>
+instead, which lets you stack multiple C<Moose.pm>-alike modules
+sanely. It handles getting the exported functions into the right place
+for you.
+
+=head2 B<throw_error>
+
+An alias for C<confess>, used by internally by Moose.
+
+=head1 METACLASS COMPATIBILITY AND MOOSE
+
+Metaclass compatibility is a thorny subject. You should start by
+reading the "About Metaclass compatibility" section in the
+C<Class::MOP> docs.
-=head2 B<init_meta ($class, $baseclass, $metaclass)>
+Moose will attempt to resolve a few cases of metaclass incompatibility
+when you set the superclasses for a class, unlike C<Class::MOP>, which
+simply dies if the metaclasses are incompatible.
-Moose does some boot strapping: it creates a metaclass object for your class,
-and then injects a C<meta> accessor into your class to retrieve it. Then it
-sets your baseclass to Moose::Object or the value you pass in unless you already
-have one. This is all done via C<init_meta> which takes the name of your class
-and optionally a baseclass and a metaclass as arguments.
+In actuality, Moose fixes incompatibility for I<all> of a class's
+metaclasses, not just the class metaclass. That includes the instance
+metaclass, attribute metaclass, as well as its constructor class and
+destructor class. However, for simplicity this discussion will just
+refer to "metaclass", meaning the class metaclass, most of the time.
+
+Moose has two algorithms for fixing metaclass incompatibility.
+
+The first algorithm is very simple. If all the metaclass for the
+parent is a I<subclass> of the child's metaclass, then we simply
+replace the child's metaclass with the parent's.
+
+The second algorithm is more complicated. It tries to determine if the
+metaclasses only "differ by roles". This means that the parent and
+child's metaclass share a common ancestor in their respective
+hierarchies, and that the subclasses under the common ancestor are
+only different because of role applications. This case is actually
+fairly common when you mix and match various C<MooseX::*> modules,
+many of which apply roles to the metaclass.
+
+If the parent and child do differ by roles, Moose replaces the
+metaclass in the child with a newly created metaclass. This metaclass
+is a subclass of the parent's metaclass, does all of the roles that
+the child's metaclass did before being replaced. Effectively, this
+means the new metaclass does all of the roles done by both the
+parent's and child's original metaclasses.
+
+Ultimately, this is all transparent to you except in the case of an
+unresolvable conflict.
=head1 CAVEATS
=item The basis of the TypeContraints module was Rob Kinyon's idea
originally, I just ran with it.
-=item Thanks to mst & chansen and the whole #moose poose for all the
+=item Thanks to mst & chansen and the whole #moose posse for all the
early ideas/feature-requests/encouragement/bug-finding.
=item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
as well as links to a number of talks and articles on Moose and Moose related
technologies.
+=item L<Moose::Cookbook> - How to cook a Moose
+
+=item The Moose is flying, a tutorial by Randal Schwartz
+
+Part 1 - L<http://www.stonehenge.com/merlyn/LinuxMag/col94.html>
+
+Part 2 - L<http://www.stonehenge.com/merlyn/LinuxMag/col95.html>
+
=item L<Class::MOP> documentation
=item The #moose channel on irc.perl.org
=item The Moose mailing list - moose@perl.org
-=item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
+=item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/moose>
-=item Several Moose extension modules in the L<MooseX::> namespace.
+=item Several Moose extension modules in the C<MooseX::> namespace.
+
+See L<http://search.cpan.org/search?query=MooseX::> for extensions.
+
+=back
+
+=head2 Books
+
+=over 4
+
+=item The Art of the MetaObject Protocol
+
+I mention this in the L<Class::MOP> docs too, this book was critical in
+the development of both modules and is highly recommended.
=back
exception. If you find a bug please either email me, or add the bug
to cpan-RT.
+=head1 FEATURE REQUESTS
+
+We are very strict about what features we add to the Moose core, especially
+the user-visible features. Instead we have made sure that the underlying
+meta-system of Moose is as extensible as possible so that you can add your
+own features easily. That said, occasionally there is a feature needed in the
+meta-system to support your planned extension, in which case you should
+either email the mailing list or join us on irc at #moose to discuss.
+
=head1 AUTHOR
Stevan Little E<lt>stevan@iinteractive.comE<gt>
Chris (perigrin) Prather
+Wallace (wreis) Reis
+
Jonathan (jrockway) Rockway
+Dave (autarch) Rolsky
+
Piotr (dexter) Roszatycki
Sam (mugwump) Vilain
projects / gitmo/Moose.git / blobdiff