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API_OBJECT.md

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Object

In this documentation object and instance are not synonym. An object can be an instance or a class, but a class is not considered to be an instance.

  • objects : everything that can be messaged, that has a class
  • class : a runtime object
  • instance : objects that are not classes

Functions

mulle_objc_object_call

void   *mulle_objc_object_call( void *obj,
                                mulle_objc_methodid_t methodid,
                                void *parameter);

The mulle-clang compiler emits this for -O0.

The non-inlining variant of sending a message to an object (calling an objects method). Parameters and return values are passed via parameter according to the MetaABI.

obj must be a pointer to a valid object or NULL.

mulle_objc_object_call_inline_partial

void  *mulle_objc_object_call_inline_partial( void *obj,
                                                             mulle_objc_methodid_t methodid,
                                                             void *parameter)

This is an optimized variant of mulle_objc_object_call in cases, where methodid is a known constant. The compiler uses this method when optimizing with -O1.

Right: mulle_objc_object_call_inline_partial( self, 0x1848, NULL), Wrong: mulle_objc_object_call_inline_partial( self, _cmd, NULL)

mulle_objc_object_call_inline

void  *mulle_objc_object_call_inline( void *obj,
                                                      mulle_objc_methodid_t methodid,
                                                      void *parameter)

This is an even further optimized variant of mulle_objc_object_call in cases, where methodid is a known constant. The compiler uses this method when optimized with -O2 and up. Frequent use of this function can increase the size of your executable by quite a bit.

Right: mulle_objc_object_call_inline( self, 0x1848, NULL), Wrong: mulle_objc_object_call_inline( self, _cmd, NULL)

mulle_objc_object_call_classid

void   *mulle_objc_object_call_classid( void *obj,
                                        mulle_objc_methodid_t methodid,
                                        void *parameter,
                                        mulle_objc_classid_t classid);

Instead of using the isa as the class to lookup the method, use the class given by classid. This is used by the compiler for super calls. It is a much slower operatin than mulle_objc_object_call.

mulle_objc_objects_call

void   mulle_objc_objects_call( void **objects, unsigned int n, mulle_objc_methodid_t methodid, void *params)

Call all n``objects with message methoid and arguments params in sequence. This method is singlethreaded and executes from the objects[ 0] up to but not including objects[ n]. It is OK, if objects contains NULL pointers.

Using mulle_objc_objects_call can be more efficient then using a boiler plate for loop yourself.

mulle_objc_object_retain

void   *mulle_objc_object_retain( void *obj)

Increment the reference count of obj. obj may be NULL. Returns obj back, this is a convenience and somewhat of an optimisation, since the caller does not not need to save obj for the call.

So obj = mulle_objc_object_retain( obj) is safe and may be faster than just mulle_objc_object_retain( obj).

mulle_objc_object_release

void   mulle_objc_object_release( void *obj)

Decrement the reference count of obj. obj may be NULL. If the reference count goes into negative, an internal version of mulle_objc_object_finalize will be called, unless mulle_objc_object_finalize has been called before on this object. If the object did not get retained during finalization, then an internal version of mulle_objc_object_dealloc is called. The object is then to be considered "dead" and must not be messaged any more.

See: mulle_objc: object layout, retain counting, finalize

mulle_objc_object_get_class

struct _mulle_objc_class   *mulle_objc_object_get_class( void *obj)

Returns the class of obj, basically what -class does. This is different than asking an obj for its isa class, becauses classes and instances both return the same class here (assert( [foo class] == [Foo class])

mulle_objc_object_get_runtime

struct _mulle_objc_runtime   *mulle_objc_object_get_runtime( void *obj)

Return the runtime, the class of obj belongs to. In mulle-objc multiple runtimes can coexist, so this is in general more correct, than just calling mulle_objc_get_runtime.

mulle_objc_object_get_isa

struct _mulle_objc_class *cls  mulle_objc_object_get_isa( void *obj)

Returns the isa class of obj. This is not necessarily the same as the isa pointer in the object header, because the function resolves tagged pointers.

mulle_objc_object_set_isa

void  mulle_objc_object_set_isa( void *obj, struct _mulle_objc_class *cls)

Change the isa of obj to cls. This will fail and raise an exception, if obj is of a tagged pointer class. If either value is NULL, the function does nothing.

mulle_objc_object_dealloc

void   mulle_objc_object_dealloc( void *obj)

A C way of calling -dealloc on an object. If you call this function yourself, you are probably "doing it wrong".

mulle_objc_object_copy

void   *mulle_objc_object_copy( void *obj)

A C way of calling -copy on an object, returns obj.

mulle_objc_object_release

void   mulle_objc_object_release( void *obj)

A C way of calling mulle_objc_object_release on an object. It's not any faster then calling -release.

mulle_objc_object_autorelease

void   *mulle_objc_object_autorelease( void *obj)

A C way of calling -autorelease on an object, returns obj.