Allocators used by the runtime

All memory location is done using mulle-allocator. There are various allocators used:

Allocator	Accessor	Description
Universe	_mulle_objc_universe_get_allocator	Used to construct classes, methodlists etc.
Foundation	_mulle_objc_universe_get_foundation_allocator	The default allocator to be placed into infraclasses
Infraclass	_mulle_objc_infraclass_get_allocator	The allocator to use for instance memory

Thoughts (not gospel)

How do you move a class with its relations to a shared memory page, to make it shareable with other processes ?

Here are the various problems. isa needs to be compatible across the runtimes. This can be accomplished by forking both processes off the same common process. If you have a class Foo with a custom allocator and it has an ivar of type NSString, the NSString must be have the same custom allocator, so it is placed in the same memory region.

What's the problem with NSZone ?

If you have a NSArray you don't copyWithZone: the elements, you retain them. But you have no control, about the NSZone those elements are in. So you have a container in one zone and elements in another, which could be bad. That's the same with allocators, but that's the reason NSZone is not exposed as concept anymore.

Use a custom allocator

• use a reference to a static allocator
• in +initialize of your class set the allocator with _mulle_objc_infraclass_set_allocator( self, &my_allocator)
• in your accessors make sure, that incoming values have been made with a compatible allocator