From: Devin Mullins <twifkak@...>
Date: 2005-09-12T05:20:21+09:00
Subject: Re: Array#[]=

Trans wrote:

>I think that you have the right sentiment, but the implemenation isn't
>so good. It would make methods more compicated things to deal with. To
>achieve signiture bases defintoins I think its best to stick with
>multiple definitions:
>  
>
There are a couple of problems with the typical definition of multiple defs:
1. Matz has said that he won't implement them. :)
2. What method are you refering to when you call method, remove_method, 
etc.? In Ruby, the method signature is its name -- changing that would 
be a bigger deal.
3. It doesn't play well with inheritance. Suddenly you've got to think 
really hard when overriding a method (making sure to remove all 
implementations with different arity, or whatever).
4. It doesn't play well with optional args and splats. My way 
establishes an obvious order of resolution -- if the first one doesn't 
match, go onto the next one. The typical way doesn't, and is one of the 
confusing things about method overloading in C++ (by type in that case, 
but same diff).

My way might squish ordef definitions together a little more (though 
you're free to use blank lines), but it maintains the idea of a method 
as an atomic unit -- the ordef thing is just an assistant to make 
dealing with different arities nice. It would make method definitions as 
complicated as you make them. If you really have one method doing three 
different things based on arity, then your central ordef thing should be 
nothing but a dispatcher to other methods.

The one problem I see with it -- not reproducible by blocks and 
define_method. But, in that case, just do it the old fashioned way, as 
has already been covered on this thread.

The other is that, if it were adopted, the next thing asked for would be 
ordef's based on ===:

def foo String => bar
ordef foo Regexp => bar
end

def foo "add" => action, *args
ordef foo "delete" => action, *args
end

And that would condone some pretty obvious smells. :)

Devin