Re: A case where Ada defaults to unsafe?

[Ted Dennison<dennison@telepath.com>]

In article <wccwuyycht9.fsf@shell01.TheWorld.com>, Robert A Duff says...
>
>Hyman Rosen <hyrosen@mail.com> writes:
>
>> But get away from C/C++ for a moment. In pure Ada terms, isn't it less safe
>> for the defaults to be "and" and "or" instead of "and then" and "or else"?
>
>I think an expression where the right-hand side is meaningful only if
>the left-hand side is True is "special" and should be marked as such
>("and then").  A more usual expression, where the two halves of "and"
>are symmetric, doesn't deserve the "extra" notation.  I guess I'm
>arguing from a readability point of view, rather than safety per se.
>But readability promotes safety in general.

Right. For example, suppose we "fix" things so that all boolean ops
short-circuit. Now there's no way for a reader to tell the difference between
boolean ops that are ordered the way they are for safety, or just accidentally.
But the most common occurance is always going to be the latter. So when Joe
Maintainence comes in and adds a condition to an "if" statement (as is *very*
common), he is now much more likely to screw up the code, since he can't tell by
just looking at it if the order of the existing conditions is important.

---
T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html

No trees were killed in the sending of this message. 
However a large number of electrons were terribly inconvenienced.