Support mapping Objective-C classes to custom ObjCInstance subclasses #81
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This is somewhat similar to the existing system for converting type encodings to ctypes types.
Their description methods return nil, which previously caused a type error when it was returned from __str__. ObjC[Meta]Class now have a custom __str__, and ObjCInstance.__str__ now detects description methods returning nil and raises a more useful exception.
| @@ -1208,7 +1259,7 @@ def __new__(cls, object_ptr, _name=None, _bases=None, _ns=None): | |||
| if is_block: | |||
| cls = ObjCBlockInstance | |||
| else: | |||
| cls = cls._select_mixin(object_ptr) | |||
| cls = type_for_objcclass(libobjc.object_getClass(object_ptr)) | |||
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Is there any reason that the is_block check couldn't be merged into type_for_objcclass?
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Yes, unfortunately. is_block is assigned at the very top of ObjCInstance.__new__, and is used to remember whether the object_ptr that was originally passed to the constructor was of type objc_block. That information would be lost otherwise, because object_ptr is cast to objc_id in the next line.
Even if that wasn't the case, type_for_objcclass takes a class pointer, and the block check happens on the instance pointer. And the reason why we have to rely on the type of the instance pointer at all is because there's no good way to tell at runtime whether an object is a block or not.
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Yeah, Mac Travis is as reliable as usual. Four of the five builds ran fine, the remaining one failed to |
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Nevermind, the build ran just now. That was much quicker than I expected. |
Yes, it's another type mapping registry. This is a replacement for
ObjCClass._select_mixin, which is not extensible and not very efficient as it grows (as I noted in #70). The new system uses a mapping to keep track of which Python type corresponds to which Objective-C class, which is more efficient and allows easy addition of extra types. This is now used internally forObjCProtocolandObjC[Mutable](List|Dict)Instance, but theoretically it can also be used externally.ObjCClass,ObjCMetaClassandObjCBlockInstaceare still special-cased inObjCInstance.__new__. They cannot be registered using the new system, because there is no single Objective-C base class for all classes, metaclasses or blocks.