On Fri, Feb 23, 2007 at 10:35:35PM -0800, Andreas Raab wrote:
> Early on I thought the same way (and this was why we started thinking 
> down that road when Nathanael interned with us). However, in practice it 
> seems like Traits are mostly being used as a thinly veiled version of MI 
> with all the same problems. You have correctly pointed out that Java 
> interfaces are "nothing but abstract virtual base classes in C++" - 
> which coincidentally, was the only way that MI ever worked in C++, which 
> itself has two dozen ways of doing MI wrong and exactly ONE to do it 
> right (abstract virtual base classes). Java choose a stand on that and 
> it worked (which is pretty impressive given that it was the first 
> language that used interface to that extent). Traits seem to reintroduce 
> a number of ways of using MI wrongly (at least that's the feeling that I 
> get when I look at the practical example) and that's why I prefer 
> interfaces.

Forgive me, but I am not familiar with "All the problems
Multiple Inheritance got wrong". I will be testing out how
Multiple Inheritance works in Squeak, since I have made it my
top priority to get ThingLab [1] working in a recent Squeak
system. ThingLab adds multiple inheritance [2] and a constraint
solver to Smalltalk, and both have at least a good theoretical
reason to be there, but I cannot test the implementation yet,
since such a change currently breaks squeak. Multiple
Inheritance has at least a solid theory; I have not had much
experience with an implementation.

[1] http://wiki.squeak.org/squeak/607
    Links to ThingLab papers and code.

[2] http://www.2share.com/thinglab/ThingLab%20-%20Chapter%203.html
    Chapter 3 of the ThingLab paper. Section 2 contains a
    defense of ThingLab's multiple inheritance.

-- 
Matthew Fulmer -- http://mtfulmer.wordpress.com/
Help improve Squeak Documentation: http://wiki.squeak.org/squeak/808