🚀 go-pugleaf

I'm making an abstract superclass whose subclasses will want to define a  
variety of processing "tools".  Each of the tools is a method; the methods have  
different names but identical declarations in terms of arg and return types.   
The superclass will ask the subclass what tool to use when, and then apply that  
tool in its operations.  If all the args were id's this would be trivial to  
implement, using Object's "perform" methods, but that's not possible in my  
situation.

It looks like the way to do it is to forward:: an unimplemented generic tool  
message from the object to itself, BUT to slip in the correct specific selector  
like this:

	- forward:(SEL)aSelector :(marg_list)argFrame
	{
	    SEL tool = [self toolForMode:mode]; // subclass method
	    if(aSelector == @selector(genericTool:::)) // unimplemented
		return [self performv:tool :argFrame];
	    return [self doesNotRecognize:aSelector];
	}

Now it is completely clear from the docs that you can performv:: the exact  
selector and arg frame passed to forward::, but it is not clear whether it is  
kosher to substitute selectors.  The forward:: docs offer the following vague  
encouragement:
	An implementation of the forward:: method can do more than just forward 
	messages.  It can, for example, locate code that responds to a variety 
	of different messages, thus avoiding the necessity of having to write a 
	separate method for each selector.

So am I asking for trouble?  This will probably work for now, but is it  
"cheating"?
--
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Paul Burchard	<burchard@math.utah.edu>
``I'm still learning how to count backwards from infinity...''
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