Re: Generics vs. Message passing: object namespaces

On 2007 Feb 23, at 10:05 PM, [email protected] wrote:
>> I find it counter-intuitive to use the same function for vastly
>> different purposes, no matter whether it is a generic one (in the
>> CLOS sense) or not.
>
>     Absolutely.  But in object dispatch obj1.foo and obj2.foo are not
> expected to do the same thing since the two foo's clearly are from two
> different namespaces, if the objects are unrelated, and thus are
> conceptually different words, whereas (foo obj1) and (foo obj2) are
> necessarily from the same namespace, without additional
> disambiguation, possibly non-local.

obj1.foo and obj2.foo are not disambiguated by obj1 or obj2, they are  
disambiguated by the types of obj1 and obj2. Information which is  
_not_ stated at the point, but yet which is required so that the  
programmer will pass the correct number and type of parameters to  
obj1.foo( ) and obj2.foo( ).

If you object to (image:draw obj1 ...) vs. (holster:draw obj2 ...)  
because having to indicate the 'source' of draw you wish to invoke is  
wordier, I agree with Pascal on that. Yawn. I'd rather see the intent  
made clear in ambiguous cases (and hence this is applicable to  
Pascal's Java MI example), for I have much more powerful ways to  
condense my code than saving one word by extracting the type of obj1/ 
obj2.

--Doug