These structures are currently handled by Foundation's BridgeSupport file
(/System/Library/Frameworks/Foundation.framework/Resources/BridgeSupport/Foundation.bridgesupport)
<struct name='NSPoint' type64='{CGPoint="x"d"y"d}'
type='{_NSPoint="x"f"y"f}'/>
<struct name='NSRange'
type64='{_NSRange="location"Q"length"Q}'
type='{_NSRange="location"I"length"I}'/>
It's not very humanly readable, but MacRuby understands what this means, and
then knows NSPoint is a structure :-).
However, just for proving myself wrong, there IS a Protocol Obj-C objet ( see
http://opensource.apple.com/source/objc4/objc4-437.1/runtime/Protocol.h ).
But I think my point stands, as I do think what is returned is the C struct,
not the class.
I think Laurent might know a little better though :-)
--
Thibault Martin-Lagardette
On Nov 17, 2010, at 12:19, Martijn Walraven wrote:
> Thanks for opening a ticket and describing the issue so well!
>
> I'm not sure how this should be solved, but I was wondering how things
> currently work for other C structs like NSRect or NSPoint. Are these handled
> as special cases, or is there a more general way to deal with C structs?
>
> Would it make sense to think about somehow mapping C structs to the Ruby
> Struct class, or maybe a special CStruct class? It would be nice if this at
> least offered a way to perform equality checks (==, eql?, equals?). For
> structs that have defined attributes it would be great if this allowed
> getting and setting attribute values (similar to what you can do with NSRect
> and NSPoint).
>
> I might be totally off, so maybe someone who knows more about the internals
> of MacRuby can comment?
>
> On Nov 17, 2010, at 11:33 , Thibault Martin-Lagardette wrote:
>
>> This is because protocols, in the Obj-C runtime, are not Obj-C objets per
>> say, they are C structs.
>> +protocolWithName returns an (id) (aka obj-c objet), but the actual returned
>> pointer is just a pointer to a C struct, which causes the runtime to issue
>> those warnings. It says "Hey, this method returned an objet, but it doesn't
>> look like one!". Which is expected, but this should be improved.
>> While it is true that in the Obj-C runtime, classes and objects are C
>> structs too, they are obviously not the same kind of structures, which is
>> why it doesn't work :-).
>>
>> In MacRuby, `Protocol` IS a real Obj-C objet, but not what the
>> +protocolWithName method returns. This means that whatever you do with the
>> returned valiue, it will crash, because it is not a real objet, and thus
>> does not respond to any message.
>> This also means that you cannot even do something like that:
>> Protocol.protocolWithName("NSCoding") ==
>> Protocol.protocolWithName("NSCoding")
>> Simply because doing this will call the `#==` method on the left-most value,
>> which is a C struct for a protocol, and not an Obj-C object.
>>
>> I created https://www.macruby.org/trac/ticket/999 , related to protocols.
>> Please be aware that the attached patch still does not make it possible to
>> override conformsToProtocol:, because calling `#==` on non-objets will
>> crash, which is why I think MacRuby could handle Protocols a little better,
>> right now I'm not sure it's "usable" per say.
>>
>> Sorry if I do repeat myself a little, but I want to make sure you understand
>> why this does not work yet, and what you can and cannot do with protocols as
>> of today :-).
>>
>> --
>> Thibault Martin-Lagardette
>
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