Re: [Rubycocoa-talk] SyncServices and RubyCocoa

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

On 8 Nov 2005, at 21:52, Rupert BARROW wrote:
>>
>>                     self.addRubyMethod_withType("#{key}".to_sym,  
>> "@4@8:12")
>>                     self.addRubyMethod_withType("# 
>> {set_key}:".to_sym, "@4@8:12@16")

>
> I tried this; here is the result :
>
> 2005-11-08 22:42:32.463 SimpleStickies[1306] KVO autonotifying only  
> supports -set<Key>: methods that return void.  Autonotifying will  
> not be done for invocations of -[Note setText:].
>
> Same error is produced for each atribute.
> What is the syntax of the second parameter to  
> 'addRubyMethod_withType' ?  It does not seem to acknowledge that  
> 'void' is returned, although the initial @ is preceded by nothing  
> (no type).

The second argument is a type encoding [1] (see also the objc_method  
documentation in [2]). It consists of a type code followed by (I  
think) some sort of stack offset. The "Special Considerations"  
section in [2] indicates that these are ignored, so you can probably  
get away with leaving them out.

The value I gave before for the setter method is incorrect - it  
declares an 'id' type return value, when it should be void. Try using  
this instead: "v@:@". This means, from left to right, v="void", @="id  
self", :="SEL _cmd", @="id value". Notice how self and selector must  
be explicitly mentioned.

[1] http://developer.apple.com/documentation/Cocoa/Conceptual/ 
ObjectiveC/RuntimeOverview/chapter_5_section_6.html

[2] http://developer.apple.com/documentation/Cocoa/Reference/ 
ObjCRuntimeRef/ObjCRuntimeRef/chapter_1.4_section_2.html

> By the way, why define "#{key}" (without ':') and "# 
> {set_key}:" (with ':') ?  [sorry for silly newbies' questions]

Don't worry, it's not obvious. The first argument is the name of the  
Objective C method to define. A method with no ':' takes no arguments  
(the getter), whereas the single : indicates that an argument follows  
it (for the setter, it's the value to set).

What we're effectively doing is programmatically making these  
Objective C class definitions for our Ruby-defined ObjC class:

   -(id)key;
   -(void)setKey:(id)value;

Cheers,
Jonathan