From: "David A. Black" <dblack@...>
Date: 2003-12-06T07:14:06+09:00
Subject: Re: Attempted roadmap of future instance variables....

Hi --

On Sat, 6 Dec 2003, Christoph wrote:

> Nathaniel Talbott wrote:
> ...
> > In this case it is trivial to alias the super-class method if 
> > I need continued access to the super-classes implementation. 
> > I don't know of a way that could be done for instance 
> > variables. More importantly, though, I think instance 
> > variables are fundamentally a different construct than 
> > methods. I'm having difficulty precisely delineating the 
> > differences (internal vs. external?), but I just don't think 
> > you can compare the potential problems from method overriding 
> > with those of instance variable shadowing. They certainly 
> > have commonalities, just as apples and oranges are both 
> > fruit, but they have quite different cores.
> 
> I am not sure if this philosophical difference
> is really so deep - in fact some languages, the 
> most widely used is probably JavaScript (okay,
> maybe that's an argument against my point:-)
> don't distinguish between data and methods
> at all. 

But at a non-philosophical level, there's a big difference in Ruby
between an instance variable and a method.  Nathaniel is right that in
discussing how to design and write Ruby classes, one can't assume that
if X is true with regard to instance variables, then X.gsub("instance
variable", "method") is true about methods :-)  Instance variables may
assist you in creating a "uniform access" environment for users of
your class (actually Ruby really does that for you, since everything
is a method call and "attributes" don't exist as separate language
constructs), but they themselves do not play the same role as
methods.  I think that's what he meant.  


David

-- 
David A. Black
dblack@wobblini.net