[chuck-users] parent and children classes (I meant polymorphism)

Kassen signal.automatique at gmail.com
Wed Jan 21 09:58:30 EST 2009


> Not sure.  It's another one of those things that I think if fairly obvious
> if you're coming from a C++ / Java-like type system, so it just seemed
> natural to me to try.
Ah, I see.

I think it was the Joker in the Tim Burton Batman film who shouted "Where
does he get those toys?" so that's where. I felt a bit like that :¬).

This needs to be documented. It's great that we have such features, it's
great that people with C/C++/Java experience can feel at home like that.
What's not so great is if stuff like this has no documentation because that
way nobody will know about it which would be a shame. I looked it up and
right now cast is only mentioned in the manual as a way to turn int's into
float's. We've seen some more examples of how it can be used but I had no
idea it was *that* general. This changes the whole "fight with the type
system game".

It is of course spectacularly un-scientific to use yourself as a test-case
and maybe my "Sherpa" title is making me vain these days but I more or less
feel that if *I* don't know about it then it must be under-documented ;¬).
We can't blame anyone for this, it's entirely logical that the developers
-who are clearly very experienced with this type of syntax- will feel some
things are so natural that they overlook mentioning them. I'll add this to
the "missing documentation" page on the wiki tonight.

I did some quick testing just now to make sure I understand it all and there
is a small issue with this in that we can now address member functions that
aren' t there which leads to crashes.

//This is fine (if pushing what's sensible to do in one line);
new SinOsc @=> UGen foo => dac;
400 => (foo $ SinOsc).freq;
second => now;

//this is not fine
UGen u;
200 => (u $ SinOsc).freq;

Of course this is rather predictable but it also means losing the whole VM
and IMHO anything that makes us lose the whole VM is a issue.

So, a new trick learned and a new way of crashing unearthed, it's a good day
for ChucKing!

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