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Date: 16 Dec 92 01:22:49 GMT
From: eachus@mitre-bedford.arpa  (Robert I. Eachus)
Subject: Re: Language pitfalls (was Re: FORTRAN bug)
Message-ID: <EACHUS.92Dec15202249@oddjob.mitre.org>
List-Id: <comp.lang.ada>

In article <1992Dec15.203558.18211@inmet.camb.inmet.com> stt@spock.camb.inmet.c
om (Tucker Taft) writes:

   Oh boy.  That is a nasty one.  This argues for a "friendly" 
   Ada compiler giving a warning about any use of "null;" other
   than the idiomatic ones like "when others => null;" or "begin null; end;"
   (especially in a function that returns an access type ;-).

   In retrospect, one could argue that it would have been better
   to have no "null" statement at all (other than simply ";") than
   to create a situation allowing this kind of one word error.

    Actually, there is an Ada rule which normally catches this, and
which Robert Dewar and I have argued should be removed in Ada 9X.  (A
function must contain a return statement RM 6.5(1).)  If it belongs on
the top ten list, then the rule should stay.

    (What Robert Dewar and I objected to was that certain functions
whose only intended effect is to raise an exception must still contain
a return statement.  This results in junk return statements in stubbed
out code, and makes a stubber much harder to write.)

--

					Robert I. Eachus

with Standard_Disclaimer;
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function Message (Text: in Clever_Ideas) return Better_Ideas is...