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Date: 10 Apr 93 15:36:50 GMT
From: mcsun!sun4nl!cwi.nl!dik@uunet.uu.net  (Dik T. Winter)
Subject: Re: and then
Message-ID: <9550@charon.cwi.nl>
List-Id: <comp.lang.ada>

In article <1q3vtq$2lt@travis.csd.harris.com> danr@ada1.ssd.csd.harris.com (Dan
 Rittersdorf) writes:
 > In article <1993Apr7.162133.3564@nosc.mil> sampson@nosc.mil (Charles H. Samp
son) writes:
...
 > >                                                       In addition, there
 > >are cases when it is unreasonable to expect such an optimization; when the
 > >second operand contains a function reference, for example.

There are other possibilities.  Short-circuiting may make the program
actually slower (jumps take time and sometimes a lot).
 > >
 >       I find it odd, though, that you feel a vendor has some *responsibility
*
 >    to provide this optimization.

There is of course no such *responsibility*, it is merely a question of
quality.  Especially as I prefer conditional tests in non-short-circuited
form if it does not matter.  In that case a good compiler would find what
is most efficient, short-circuiting or not.  Short-circuiting should only
be used where it matters for the logic of the program (e.g. the second
operand becomes invalid).
-- 
dik t. winter, cwi, kruislaan 413, 1098 sj  amsterdam, nederland
home: bovenover 215, 1025 jn  amsterdam, nederland; e-mail: dik@cwi.nl