Re: [Rubycocoa-talk] return simple int from Ruby to ObjC

[Laurent S. <lsa...@ap...>]

When creating a Ruby method like this, without providing its ObjC  
runtime signature, RubyCocoa will assume that all arguments and the  
return value are Objective-C objects (of the type 'id'). Because there  
is no way for RubyCocoa to know. This is why you get from the ObjC  
world an NSNumber and not an "int".

To work around this, you need to register the Ruby method into the  
ObjC runtime:

   def getInt ... end
   objc_method :getInt, 'int'

This will register getInt as a method that doesn't take any argument  
and returns a C integer.

Usually when you are overriding an ObjC method from Ruby, or  
implementing an ObjC informal protocol in Ruby, you don't need to use  
objc_method. But in this special case, it is required. Fortunately,  
most people won't need to use it.

Laurent

On Jul 15, 2007, at 3:01 PM, Motohiro Takayama wrote:

> Hi,
>
> I'm wondering how to return simple "int" type value from Ruby code to
> Objective-C code.
> Ruby code passes Fixnum, and Objective-C code recieves NSCFNumber
> instead of simple int.
> Any suggestion ?
>
>
> Ruby code:
>
>  class Hoge < OSX::NSObject
>    def getInt
>      5
>    end
>  end
>
>
> Objective-C code:
>
> 	Class helper = NSClassFromString(@"Hoge");
> 	id hoge = [[helper alloc] init];
> 	NSLog(@"%@ %d", [[hoge getInt] class], [(NSNumber *)[hoge getInt]
> decimalValue]);
>
>
> and those show:
>
>  2007-07-15 21:52:56.954 retval[5100] NSCFNumber 8448
>
>
> thanks,
>
> --
> Motohiro Takayama
> http://blog.deadbeaf.org/
>
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