NAME

Object::Pad::MOP::Class - meta-object representation of a Object::Pad class

DESCRIPTION

Instances of this class represent a class or role implemented by Object::Pad. Accessors provide information about the class or role, and methods that can alter the class, typically by adding new elements to it, allow a program to extend existing classes.

Where possible, this API is designed to be compatible with MOP::Class.

This API should be considered experimental, and will emit warnings to that effect. They can be silenced with

   use Object::Pad qw( :experimental(mop) );

or

   use Object::Pad::MOP::Class qw( :experimental(mop) );

CONSTRUCTOR

for_class

   $metaclass = Object::Pad::MOP::Class->for_class( $class )

Since version 0.38.

Returns the metaclass instance associated with the given class name.

for_caller

   $metaclass = Object::Pad::MOP::Class->for_caller;

Since version 0.38.

A convenient shortcut for obtaining the metaclass instance of the calling package scope. Often handy during BEGIN blocks of the class itself to perform adjustments or additions.

   class Some::Class::Here 1.234 {
      BEGIN {
         my $meta = Object::Pad::MOP::Class->for_caller;
         ...
      }
   }

create_class

   my $metaclass = Object::Pad::MOP::Class->create_class( $name, %args )

Since version 0.61.

Creates a new class of the given name and yields the metaclass for it.

Takes the following additional named arguments:

extends => STRING
isa => STRING

An optional name of a superclass that this class will extend. These options are synonyms; new code should use isa, as extends will eventually be removed.

Once created, this metaclass must be sealed using the "seal" method before it can be used to actually construct object instances.

create_role

   my $metaclass = Object::Pad::MOP::Class->create_role( $name, %args )

Since version 0.61.

As "create_class" but creates a role instead of a class.

begin_class

   BEGIN {
      my $metaclass = Object::Pad::MOP::Class->begin_class( $name, %args )
      ...
   }

Since version 0.46.

A variant of "create_class" which sets the newly-created class as the current complication scope of the surrounding code, allowing it to accept Object::Pad syntax forms such as has and method.

This must be done during BEGIN time because of this compiletime effect. It additionally creates a deferred code block at UNITCHECK time of its surrounding scope, which is used to finalise the constructed class. In this case you do not need to remember to call "seal" on it; this happens automatically.

begin_role

Since version 0.46.

As "begin_class" but creates a role instead of a class.

METHODS

is_class

is_role

   $bool = $metaclass->is_class
   $bool = $metaclass->is_role

Exactly one of these methods will return true, depending on whether this metaclass instance represents a true class, or a role.

name

   $name = $metaclass->name

Returns the name of the class, as a plain string.

superclasses

   @classes = $metaclass->superclasses

Returns a list of superclasses, as Object::Pad::MOP::Class instances.

Because Object::Pad does not support multiple superclasses, this list will contain at most one item.

direct_roles

   @roles = $metaclass->direct_roles

Returns a list of the roles introduced by this class (i.e. added by `does` declarations but not inherited from the superclass), as Object::Pad::MOP::Class instances.

This method is also aliased as roles.

all_roles

   @roles = $metaclass->all_roles

Since version 0.56.

Returns a list of all the roles implemented by this class (i.e. including those inherited from the superclass), as Object::Pad::MOP::Class instances.

add_role

   $metaclass->add_role( $rolename )
   $metaclass->add_role( $rolemeta )

Since version 0.56.

Adds a new role to the list of those implemented by the class.

The new role can be specified either as a plain string giving its name, or as an Object::Pad::MOP::Class meta instance directly.

Before version 0.56 this was called compose_role.

add_BUILD

   $metaclass->add_BUILD( $code )

Adds a new BUILD block to the class, as a CODE reference.

add_method

   $metamethod = $metaclass->add_method( $name, %args, $code )

Adds a new named method to the class under the given name, as CODE reference.

Returns an instance of Object::Pad::MOP::Method to represent it.

Recognises the following additional named arguments:

common => BOOL

Since version 0.62.

If true, the method is a class-common method.

get_direct_method

   $metamethod = $metaclass->get_direct_method( $name )

Returns an instance of Object::Pad::MOP::Method to represent the method of the given name, if one exists. If not an exception is thrown.

This can only see directly-applied methods; that is, methods created by the method keyword on the class itself, or added via "add_method". This will not see other names in the package stash, even if they contain a CODE slot, nor will it see methods inherited from a superclass.

This is also aliased as get_own_method for compatibility with the MOP::Class interface.

get_method

   $metamethod = $metaclass->get_method( $name )

Since version 0.57.

Returns an instance of Object::Pad::MOP::Method to represent the method of the given name, if one exists. If not an exception is thrown.

This will additionally search superclasses, and may return a method belonging to a parent class.

direct_methods

   @metamethods = $metaclass->direct_methods

Since version 0.57.

Returns a list of Object::Pad::MOP::Method instances to represent all the direct methods of the class. This list may be empty.

all_methods

   @metamethods = $metaclass->all_methods

Since version 0.57.

Returns a list of Object::Pad::MOP::Method instances to represent all the methods of the class, including those inherited from superclasses. This list may be empty.

add_field

   $metafield = $metaclass->add_field( $name, %args )

since version 0.60.

Adds a new field to the class, using the given name (which must begin with the sigil character $, @ or %).

Recognises the following additional named arguments:

default => SCALAR

Since version 0.43.

Provides a default value for the field; similar to using the syntax

   has $field = SCALAR;

This value may be undef, to set the value as being optional if it additionally has a parameter name.

param => STRING

Since version 0.43.

Provides a parameter name for the field; similar to setting it using the :param attribute. This parameter will be required unless a default value is set (such value may still be undef).

reader => STRING
writer => STRING
mutator => STRING

Since version 0.46.

accessor => STRING

Since version 0.56.

Provides method names for generated reader, writer, lvalue-mutator or reader+writer accessor methods, similar to setting them via the :reader, :writer, :mutator or :accessor attributes.

weak => BOOL

Since version 0.46.

If true, reference values assigned into the field by the constructor or accessor methods will be weakened, similar to setting the :weak attribute.

Returns an instance of Object::Pad::MOP::Field to represent it.

add_slot

   $metafield = $metaclass->add_slot( $name, %args )

Now deprecated.

Back-compatibility alias for add_field.

get_field

   $metafield = $metaclass->get_field( $name )

Since version 0.60.

Returns an instance of Object::Pad::MOP::Field to represent the field of the given name, if one exists. If not an exception is thrown.

get_slot

   $metafield = $metaclass->get_slot( $name )

Now deprecated.

Back-compatibility alias for get_field.

fields

   @metafields = $metaclass->fields

Since version 0.60.

Returns a list of Object::Pad::MOP::Field instances to represent all the fields of the class. This list may be empty.

slots

   @metafields = $metaclass->slots

Since version 0.42; now deprecated.

Back-compatibility alias for fields.

add_required_method

   $metaclass->add_required_method( $name )

Since version 0.61.

Adds a new required method to the role, whose name is given as a plain string.

Currently returns nothing. This should be considered temporary, as eventually a metatype for required methods will be added, at which point this method can return instances of it. It may also take additional parameters to define the required method with. Currently extra parameters are not permitted.

required_method_names

   @names = $metaclass->required_method_names

Since version 0.61.

Returns a list names of required methods for the role, as plain strings.

This should be considered a temporary method. Currently there is no metatype for required methods, so they are represented as plain strings. Eventually a type may be defined and a required_methods method will be added.

seal

   $metaclass->seal

Since version 0.61.

If the metaclass was created by "create_class" or "create_role", this method must be called once everything has been added into it, as the class will not yet be ready to construct actual object instances before this is done.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>