[2231] in java-interest
RE: interfaces are NO substitution for method pointers
daemon@ATHENA.MIT.EDU (Tako Schotanus)
Wed Sep 27 07:34:48 1995
From: Tako Schotanus <Tako.Schotanus@bouw.tno.nl>
To: "'Ken Arnold - Sun Labs'" <arnold@cocolat.East.Sun.COM>,
"java-interest@java.Eng.Sun.COM" <java-interest@java.Eng.Sun.COM>
Date: Wed, 27 Sep 1995 10:03:00 +-100
>I suppose I'm not as wise as Arthur -- I'm going to take *one* crack
>at trying to convince.
>
>Using methods, if you want, say, a callback from a button click, you
>say something like this (in the officially approved signature):
>
> void CancelButtonCallbackFunc(Button *button, void *my_data)
> {
> do_cancel((Operation *) my_data); // whatever
> }
>
>Using an interface, it would look like this:
>
> class CancelButtonCallback extends Button {
> Operation *my_data;
>
> void pressed()
> {
> do_cancel(); // whatever
> }
> }
[stuff deleted]
>At the very worst, you can argue that the new system maybe has a very
>few more keystrokes. You have to admit that it adds some type safety,
>and arguably OO cleanliness and reusability. This doesn't sound like a
>problem to me. In fact, it smells a lot like a *solution* to some
>problems.
Except of course that you might want to dynamically assign callback functions.
Now if somebody could explain to me how do *that* in an OO way I'd be very
happy to hear it. ;)
- Tako
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