I just pushed a fix for this which checks if the class, or instance, implements
the required methods for the protocol given to conformsToProtocol:. Please give
it a try :)
Eloy
On 22 nov 2010, at 02:53, Laurent Sansonetti wrote:
> I commented the #999 ticket, I believe there is a way to make MacRuby classes
> automatically conform to protocols (once all required methods are
> implemented).
>
> Let's try to get that done for the upcoming release :)
>
> Laurent
>
> On Nov 20, 2010, at 2:28 PM, Charles Steinman wrote:
>
>> In case anyone needs it in the meantime, here is a working
>> implementation of conformsToProtocol:
>>
>> def conformsToProtocol(protocol)
>> supported = %w( AProtocol SomeOtherProtocol YetAnotherProtocol
>> ).map {|name| Protocol.protocolWithName name} # List the protocols you
>> want to conform to between the parns
>> supported.any? {|candidate| protocol.isEqual candidate } or super
>> end
>>
>> The reason this works is because Protocol *is* a real class, but it's
>> derived from a base class different from NSObject. Obviously we'll
>> want a better solution for MacRuby, but this will work in the
>> meantime.
>>
>> — Chuck
>>
>> On Wed, Nov 17, 2010 at 4:42 AM, Eloy Duran <eloy.de.en...@gmail.com> wrote:
>>> Regardless of the current state, having a real Protocol class and objects
>>> that you can use to check against should be the goal. Let's discuss this
>>> further on the ticket from now on, for completeness sake.
>>> On Nov 17, 2010, at 12:44 PM, Thibault Martin-Lagardette wrote:
>>>
>>> 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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