Object-c Runtime from code to code

In relation to object C in object, class, Meta class, the following call is in the source code of OBJC4:

After the LIBOBJC Dynamic library is called, the following function calls in turn

Asm

_map_images:

...

JMP _map_2_images

Map_2_images

Map_images_nolock

_read_images

_objc_connect_classes_from_image

Connect_class

Really_connect_class

Set_superclass

/***********************************************************************

* Objc_allocateclass.

**********************************************************************/

void Set_superclass (class CLS, class Supercls, bool cls_is_new)

{

Class meta = cls->ISA();

if (supercls) {

cls->Superclass = supercls;

meta->Superclass = supercls->ISA();

Meta->Initisa(supercls->Isa (), ISA ());

//Propagate C + + cdtors from superclass.

if (supercls->info & cls_has_cxx_structors) {

if (cls_is_new) cls->info |= cls_has_cxx_structors;

else cls->setInfo(cls_has_cxx_structors);

}

//Superclass is no longer a leaf for cache flushing

if (supercls->info & cls_leaf) {

Supercls->clearinfo(cls_leaf);

Supercls->ISA(),clearinfo(cls_leaf);

}

} Else {

cls->Superclass = Nil; //Superclass of root class is nil

meta->Superclass = CLS; //Superclass of root metaclass is root class

Meta->Initisa(meta); //Metaclass of root metaclass is root metaclass

//Root class is never a leaf for cache flushing, because the

//Root metaclass is a subclass. (This could is optimized, but

//is too uncommon to bother.)

Cls->clearinfo(cls_leaf);

Meta->clearinfo(cls_leaf);

}

}

The annotations in Set_superclass clearly describe the relationship and assignment between class, Meta Class, class Isa, Meta Isa, class Super class, Meta Super class, and so on.

Object-c Runtime from code to code