Re: Building blocks (Was: Design By Contract)

[jsa@alexandria.organon.com (Jon S Anthony)]

In article <EG9ruK.BIq@world.std.com> bobduff@world.std.com (Robert A Duff) writes:

> >> It would be cool if you could check at compile time that all exceptions
> >> were being handled by the client, and that only the exceptions advertised
> >> by a supplier get raised (and only in the specified state).  Maybe that's
> >> the Eiffel model already.
> >
> >Well, that's one good thing you can say about Java.  Or is it (good)?
> 
> No, it's not good.  It leads to "crying wolf" -- that is, one must state
> that so-and-so might raise such-and-such exception, even when it's
> obvious it won't.  Consider, for example, the stream classes in Java.  A
> stream that represents a sequence of bytes read from an in-memory array
> has to falsely state that it might raise various I/O related exceptions,
> despite the fact that it has nothing whatsoever to do with I/O.
> 
> The sentiment here is good, but it doesn't work given the paricular
> rules of Java, IMHO.  Perhaps a different set of language rules could
> achieve the benefits without the "crying wolf" problems.

CORBA IDL has this same problem.  Actually, it may have influenced the
Java model as it certainly came B4 Java (I wonder if this bit of IDL
can be traced back to Sun....)

/Jon

-- 
Jon Anthony
OMI, Belmont, MA 02178, 617.484.3383 
"Nightmares - Ha!  The way my life's been going lately,
 Who'd notice?"  -- Londo Mollari