Message-Id: <9605131903.AA18563@lusitania.watson.ibm.com>
To: caml-list@pauillac.inria.fr
Subject: Re: Class variables in O'Caml
Date: Mon, 13 May 1996 15:03:12 -0400
From: Chet Murthy <chet@watson.ibm.com>
Jerome Vouillon writes
::On Fri, 10 May 1996, Thorsten Ohl wrote:
::>
::> >>>>> "Christian" == Christian Boos <boos@gr6.u-strasbg.fr> writes:
::>
::> Christian> IMO, the use of references is not so unnatural. Together
::> Christian> with structs, it provides a clean way to encapsulate global
::> Christian> state and actions for classes.
::>
::> Sure, it us possible to do it. But, IMHO, class variables should be
::> declared in the class and be opaque. If you put several classes in a
::> module, the use of module wide references makes much less sense.
::> Another hack is to define a sub-module for each class, but that's not
::> nice either ...
::>
::> I'm just curious if (and why) this syntactic sugar has been left out
::> intentionally.
::
::It has not been left out intentionally. Many object-oriented languages
::(C++, Objective C and Modula 3, for instance) do not have class variables,
::so I did not even thought of adding them.
::But I do not plan to implement class variables. I don't want to add too
::many features, and I don't think they are an important one: in my
::opinion, they are not commonly used, and they can be easily simulated
::using references as you noticed.
::
:: Jerome Vouillon
Actually, C++ statics are class variables. I would not be surprised
if Objective-C had them, too, given that Java has them too. (I haven't
looked at ObjC doce in a long time)
Class variables are valuable syntactic sugar, because they group the
mutable, but shared, state of a class together, in a way which is
difficult for a naive programmer to ignore.
In the commercial world, it seems that such function, while admittedly
syntactic sugar, is important.
I guess what I'm saying is, it would be a really nice thing if O'Caml
has them -- it would make it much easier to sell to the commercial
sector.
--chet--