Re: [Rubycocoa-talk] Cocoa-ized return values from methods

[Jonathan P. <jp...@dc...>]

On 22 Aug 2005, at 17:45, Steven Arnold wrote:
>
> When I call self.getFormValues, I do not get back a Ruby Hash, but  
> rather a Cocoa NSCFDictionary.  Right before the return, it's a  
> hash....but when it gets back, it's an NSCFDictionary.

Could you include the exact code you're using when calling  
getFormValues? The behaviour ought to be as you're hoping, but it  
won't if the method call is going via the Objective C bridge.

The effects you're seeing should only occur if the method call goes  
via the objective-c bridge. For normal method calls directly on a  
ruby object when the target method is implemented in ruby, it  
shouldn't get involved. The bridge is implemented by hooking into  
method_missing, so it gets involved when the method can't be found in  
ruby.

You can force the bridge to get involved by prefixing the method name  
with 'oc_', which is a special case. Since a method with this name  
doesn't exist, the Objective C bridge will get invoked, and it strips  
the 'oc_' prefix. It converts arguments and return values to and from  
Objective C, makes the Objective C call, which ends up getting routed  
back to the ruby code.

For example:

class X < OSX::NSObject
   def getHash
     {}
   end

   def me
     self
   end

   def selfGetHash
     self.getHash
   end
end

x = X.alloc.init
x.getHash #=> {}
x.me #=> #<X:0x812db2 class='X' id=0x12a02f0>
x.selfGetHash #=> {}

x.oc_me #=>  #<X:0x812db2 class='X' id=0x12a02f0>
x.oc_getHash #=> #<OSX::OCObject:0x80e596 class='NSCFDictionary'  
id=0x12a9f30>
x.oc_selfGetHash #=> #<OSX::OCObject:0x80d844 class='NSCFDictionary'  
id=0x12abc30>


Can you confirm that the above code behaves as expected?

Thanks
Jonathan