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Re: Tim Sweeney on Programming Languages
So it's a linker-level technology. When I was writing Java (wonderful use of
past tense there :-) ) we used to swap classes and search paths around, and
dynamically load classes by generated names. You could do this because the
linker allowed you to do this.
Shared libraries for other languages (including Dylan) allow similar
techniques.
I don't feel this is what Sweeny is getting at though. I feel like a
procedural programmer at their first Object lecture going "they're just
structs, aren't they?".
- Rob.
Maarten Hazewinkel wrote:
> In article <200002071845.NAA18229@life.ai.mit.edu>,
> Michael Schuerig <schuerig@acm.org> wrote:
>
> >I agree in principle, but not in practice. The mechanism that Sweeney
> >proposes is not much better than interfaces and factories. The point is
> >that both require forethought. You have to explicitly use his "virtual
> >classes" to reap their benefits. If you didn't think of this, you're as
> >much out of luck as with any other approach.
>
> Perhaps the word 'virtual' has too many C++ associations, and implies that
> you have to declare in the base class that something can be overridden.
> Fortunately that practice doesn't extend much beyond C++.
>
> I see nothing in Sweeneys idea that requires a declaration in the classes
> of the base framework to allow them to be used as virtual classes. Not even
> the framework declarations need to be provided by the writer of of original
> classes. You can simply take a group of classes (a library) and declare
> that to be the base framework, then derive your own framework from that.
>
> Thinking about it, this is something that can even be supported outside of
> the language. It could be supported at the IDE level by some grouping
> mechanisms and some clever substitution of classes during compilation.
> Though you would have standarization problems that way, it could be
> implemented in a couple of weeks by someone familiar with the innner
> workings of the IDE. No rocket science required.
>
> Maarten
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