From: Tom Sawyer <transami@...>
Date: 2002-09-13T08:36:29+09:00
Subject: Re: not grasping the method overloading/multi-dispatch thing

On Thu, 2002-09-12 at 17:09, Albert Wagner wrote:

> That is true.  Yet, there is an implied contract where arg1 and arg2 must 
> respond to #to_s.  As a mind game, assuming that argument typing were really 
> desirable, and forgetting for a moment the objections,  what would be a cool 
> way to specify the _behaviour_ expected from argument objects?  (Not using 
> initializing code like #responds_to, etc.)  Smalltalkers tended to adopt the 
> convention of prefixing a class name with a- or an- (aString, anInteger); but 
> Smalltalk was single inheritance, without mixins. 

that's an interesting question. so rather then meth(Integer i) meaning i
is kind_of Integer, rather it should mean responds_to all the same
methods as Integer?

but how do you take only a intersection of it? perhaps not perfect but
set theory might be useful, though perhap a bit odd. (borrowing from
array):

	def meth(Integer & Array i)

meaning i is something that responds to the methods common to Integer
and Array. odd isn't it? of course other set operators could be used.
and you could define "TypeMaps", essentially empoty classes with dummy
methods just for this purpose.

my only problem with the whole type vs. calss argument, is what if two
objects have two differnt method with the same name that return
completly different types or classes of object? so return values need to
be taken into consideration too. in fact that's really wahts important
--not that the methods have the same name, but that they produce the
same type or class (which? both?) of thing.

this is getting messy.

-- 
tom sawyer, aka transami
transami@transami.net