Re: Generics vs. Message passing: object namespaces

On 23 Feb 2007, at 2:23 PM, Pascal Costanza wrote:
>Sooner or later, the libraries of some language will grow bigger, and
then sooner or later, you need objects that adhere to incompatible
interfaces (messages that happen to have the same name but are used for
different purposes). You can then either choose to distribute the
functionality across several objects, and get object identity problems
along the way, or you can choose to incorporate proper namespace
management.

    This is a weak argument, because that point is 'sooner' with
CLOS-style generics and 'later' with OO namespaces.  You can argue
that many OO languages lack 'proper' namespace management, that is, a
single elegant solution that solves everything, but if this lack shows
up further on the scaling path than in CLOS, it indicates that the
modularization provided by objects may not be perfect but it *is* a
partial solution that may be good enough 90% of the time.  It may also
be possible to extend or enhance the system to be a 'proper' one --
the idea may not be a mistake that must be undone with a completely
different system.  But the semantics of object dispatch seem to mostly
solve a problem that in a CLOS-like world require appeal to a second
mechanism.

    You can also put aside pragmatics and argue that providing namespaces
automatically with objects is a natural and desirable feature. 
Scoping to the object may not always be the right thing to do (and
thus may be overused) but it is hard to imagine that it is not
generally useful.

    DING!  I declare this round goes to object dispatch.