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Class

The class is the central data structure, that manages objects. Since the fundamental structure of the Mac OS X runtime and the mulle-objc runtime is very similiar, it makes sense to read this introduction to classes: What is a meta-class in Objective-C?

Nevertheless here are some definitions:

Name Definition
class A class is one of a classpair
classpair A classpair consists of an infraclass and a metaclass.
infraclass Often just synonym with class, this holds the methods for instances (like -dealloc)
metaclass This holds the methods for classes (like +alloc)
superclass The class a class inherits from (@interface Foo : Bar // Bar is the superclass)
protocol A protocol is a unique id, that tags a classpair. You can ask a class if it conforms to a protocol (has this tag)
category An extension of a classpair, that adds methods to it

Functions

All functions allow a NULL argument for cls. The return value will be 0, except where indicated otherwise.

mulle_objc_class_add_methodlist

int   mulle_objc_class_add_methodlist( struct _mulle_objc_class *cls,
                                       struct _mulle_objc_methodlist *list)

Add methodlist list to cls. The methodlist isn't copied, so be sure that is sticks around for the lifetime of the runtime. (Check out mulle_objc_universe_add_gift_nofail)

mulle_objc_classpair_add_protocolid

void   mulle_objc_classpair_add_protocolid( struct _mulle_objc_class *cls,
mulle_objc_protocolid_t protocolid)

Add protocolid to class cls. The protocolid should be added to the infraclass and to the metaclass using two calls to mulle_objc_class_add_protocol. The function does not check for duplicates.

mulle_objc_class_get_superclass

struct _mulle_objc_class   *mulle_objc_class_get_superclass( struct _mulle_objc_class *cls)

Return the superclass of cls. If cls is a root class, it will return NULL.

mulle_objc_class_get_classid

mulle_objc_classid_t   mulle_objc_class_get_classid( struct _mulle_objc_class *cls)

Return the classid of cls. This is the unique identifying hash of the class. It can also be computed by calling mulle_objc_classid_from_string on the name of the class.

mulle_objc_class_get_name

char   *mulle_objc_class_get_name( struct _mulle_objc_class *cls)

Get the name of the class.

mulle_objc_class_get_runtime

struct _mulle_objc_runtime   *mulle_objc_class_get_runtime( struct _mulle_objc_class *cls)

Get the runtime cls is a part of. It is possible to have multiple runtimes, and calling mulle_objc_class_get_runtime on cls is the preferred way of getting access to the runtime pointer.

mulle_objc_class_get_instance_size

size_t   mulle_objc_class_get_instance_size( struct _mulle_objc_class *cls)

Returns the size of cls instances. The returned value is different if you query the infraclass or the metaclass. Returns (size_t) -1 if cls is NULL. You usually want to ask the infraclass:

A class with no instance variables with return 0.

Example:

cls = mulle_objc_object_get_class( obj);
printf( "Instance size: %ld\n", (long) mulle_objc_class_get_instance_size( cls));

mulle_objc_class_get_inheritance

unsigned int   mulle_objc_class_get_inheritance( struct _mulle_objc_class *cls)

Returns the way methods are inherited from superclasses and categories. The returned value is a combination of the following bits:

enum
{
   MULLE_OBJC_CLASS_DONT_INHERIT_SUPERCLASS          = 0x01,
   MULLE_OBJC_CLASS_DONT_INHERIT_CATEGORIES          = 0x02,
   MULLE_OBJC_CLASS_DONT_INHERIT_PROTOCOLS           = 0x04,
   MULLE_OBJC_CLASS_DONT_INHERIT_PROTOCOL_CATEGORIES = 0x08
};

Returns ~0 (all unsigned int bits set) if cls is NULL.

mulle_objc_class_get_forwardmethod

struct _mulle_objc_method   *mulle_objc_class_get_forwardmethod( struct _mulle_objc_class *cls)

Returns the method used for forwarding. Forwarding happens when you message an object with a method it doesn't support. In this case the forward method is called.

mulle_objc_class_is_infraclass

int   mulle_objc_class_is_infraclass( struct _mulle_objc_class *cls)

Returns 1 if cls is an infraclass. The infraclass is what you get, when you call mulle_objc_object_get_class.

mulle_objc_class_is_metaclass

int   mulle_objc_class_is_metaclass( struct _mulle_objc_class *cls)

Returns 1 if cls is a metaclass.

mulle_objc_class_get_infraclass

struct _mulle_objc_class   *mulle_objc_class_get_infraclass( struct _mulle_objc_class *cls)

Given any class of a classpair, returns the infraclass.

mulle_objc_class_get_metaclass

struct _mulle_objc_class   *mulle_objc_class_get_metaclass( struct _mulle_objc_class *cls)

Given any class of a classpair, returns the metaclass.

mulle_objc_class_conforms_to_protocol

int   mulle_objc_class_conforms_to_protocol( struct _mulle_objc_class *cls, mulle_objc_protocolid_t protocolid)

Returns 1 if cls conforms to a protocol with protocolid. This can be asked off the metaclass and the infraclass with the same result. You can get the propertyid for a property by its name using mulle_objc_protocolid_from_string.

mulle_objc_class_search_property

struct _mulle_objc_property  *mulle_objc_class_search_property(
                                 struct _mulle_objc_class *cls,
                                 mulle_objc_propertyid_t propertyid);

Search for a property with propertyid in cls. You can get the propertyid for a property by its name using mulle_objc_protocolid_from_string. The returned property can then be used for further introspection.

mulle_objc_class_search_ivar

struct _mulle_objc_ivar  *mulle_objc_class_search_ivar( struct _mulle_objc_class *cls,
                                                        mulle_objc_ivarid_t ivarid);

Search for an instance variable with ivarid in cls. You can get the ivarid for a ivar by its name using mulle_objc_ivarid_from_string. The returned property can then be used for further introspection.