Re: Multiple Inheritance in Ada 9X/Pointers?

[agate!tully.CS.Berkeley.EDU!hilfingr@ames.arc.nasa.gov (Paul N. Hilfinge]

In article <1992Jan06.185123.188@microsoft.com> jimad@microsoft.com
(Jim ADCOCK) writes:

|> >Perhaps we should be discussing doing away
|> >with pointers in C++ -- not MI !?

to which, in article <1992Jan8.153857.26769@cis.ohio-state.edu>,
weide@elephant.cis.ohio-state.edu (Bruce Weide) responds:

|> Not a bad idea!  ... what about a software discipline that says, "Don't
|> USE pointers."

I don't think that is the right topic.  People often incorrectly
formulate the old structured coding doctrine as "don't use goto's",
whereas it was more properly seen as the POSTIIVE statement "use the
most appropriate control structure (which happens almost never to be
'goto')".  It is fair to say, I think, that use of the goto declined
markedly, even though there are few languages in which it has been
eliminated.

Here, likewise, the more interesting topic is "what dynamic data types
SHOULD we use for applications where we now use pointers?"

A related comment and question: The statement "pointers are a (the
most) dangerous feature in ..." is part of that portion of the folk
wisdom that I most distrust---the plausible but untested (and often
unexamined) broad claims that tend to get chorused by all us
educators.  Can anyone point me at good empirical studies of the
frequency of errors in real code produced by experienced programmers
that are caused by, e.g., using pointers instead of something more
appropriate?  Studies that show that, e.g., X% of errors are pointer-
related or Y% of debugging time is spent tracing pointer-related
errors are useful, but not completely satisfactory, since they lack
controls (where would the errors be using alternative data
structures).
 
-- 

Paul N. Hilfinger, Associate Professor		(510) 642-8401        
Computer Science Division			Hilfinger@CS.Berkeley.EDU
Dept. of Electrical Engineering and Computer Sciences
University of California
Berkeley, CA  94720