Re: Cocoa et al as HCI usability problem

FROM : Jean-Daniel Dupas
DATE : Mon May 19 22:58:11 2008

Le 19 mai 08 à 22:36, Peter Duniho a écrit :

>> Date: Mon, 19 May 2008 20:31:02 +0200
>> From: Andreas Mayer <<email_removed>>
>>
>> This is (part of) a method that handles an AppleScript command send 
>> to
>> the application.
>> One possible argument is the color to be used for display:
>>
>> - (id)handleDisplayCommand:(NSScriptCommand *)command
>> {
>>     NSDictionary *args = [command evaluatedArguments];
>>     NSString *colorName = [args objectForKey:@"color"];
>>     NSColor *color;
>>
>>     ...
>>
>>     if (colorName) {
>>         SEL colorSelector = NSSelectorFromString([colorName
>> stringByAppendingString:@"Color"]);
>>         if ([[NSColor class] respondsToSelector:colorSelector]) {
>>             color = objc_msgSend([NSColor class], colorSelector);
>>         }
>>     }
>>
>>     ...
>> }
>>
>> This way you may use any color name that NSColor supports.

>
> In .NET, you'd just call Color.FromName().
>
> More generally, as before, any code that is simply checking 
> "respondsToSelector" and then calling the specific selector, that 
> can easily be implemented in C# or Java using reflection (assuming 
> there's not a better, more idiomatic approach in those languages, as 
> often there would be).  And situations when one would need this are 
> generally far and few between (i.e. not common enough to dictate an 
> entire language paradigm), especially when a class has the foresight 
> to implement that kind of functionality already.
>
> I appreciate the example.  It's certainly reasonably elegant and to 
> the point, and it's more "real world" than some of the other ones 
> (bridging Cocoa to another language?  yeah, right...a) it's not like 
> you can't interface between languages with other languages, and b) 
> this is not the kind of thing one is going to see in general 
> application code).  But not the sort of compelling "we really need 
> the language to be this way otherwise it just doesn't work" example 
> I was hoping for.


See NSDistributedObject and more generaly NSProxy for example.