phys169@csc.canterbury.ac.nz (01/25/91)
This is all getting very silly. Reminds me of the COME-FROM that was suggested
after an even sillier discussion of goto's. Anyone remember that?? Since this
topic never seems to die, for those wishing to skip boring postings on the
subject, here's by method:
If the person... Then...
Hates GOTO but likes EXIT/BREAK Ignore the idiot, he can't see the similarity.
Hates GOTO (no word of EXIT) Probably an even greater idiot, who hasn't
even heard of EXIT or BREAK
Hates GOTO and EXIT and BREAK Probably never written a real program. Ignore!
Likes GOTO but not EXIT/BREAK Great idiot who only knows BASIC, listen to
them very carefully - might be your boss!
(Purely humerous; no similarity to persons living or dead, etc)
Seriously, making hard and fast generalizations about people like this is as
bad as generalisations about programs with GOTO's. In some classes of problem,
a goto is very good, and simplifies the program (often in error conditions or
process control applications). But most often, a goto simply indicates sloppy
thinking. maine@elxsi.dfrf.nasa.gov (Richard Maine) (01/25/91)
On 25 Jan 91 05:15:17 GMT, phys169@csc.canterbury.ac.nz said: phys169> This is all getting very silly. Reminds me of the COME-FROM phys169> that was suggested after an even sillier discussion of phys169> goto's. Anyone remember that?? Would you believe that I've used a Fortran compiler that actually implemented the comefrom statement? It was not a documented feature, just a bit of insider humor on the part of the compiler writers. On a hint, I tried it out and it really worked. (No, I was not silly enough to use it on "real" programs, though for a while I kept a little sample around to amuse people with). I think it disappeared soon after a customer submitted a bug report relating to it! If I recall, the bug report had something to do with the optimizer not recognizing loops implemented with comefroms, making them run slower than loops done with gotos or do statements. (I may not have this part 100% right). The machine was an Elxsi 6400, which we still have (yes its the one my email address below shows). I forget the version of the compiler, but it was probably about 3-4 years ago. -- Rich Maine maine@elxsi.dfrf.nasa.gov
elmo@troi.cc.rochester.edu (Eric Cabot) (01/26/91)
While we are on the subject of Exit, I really miss the form of
Exit used by UCSD pascal-whereby you could exit out of several
nested procedures. Although I happily switched to Turbo
years ago, the UCSD version is, IMHO, far more general and useful.
Here's an example of how it worked:
Program non_turbo_exit;
procedure a;
procedure b;
procedure c;
begin (*c*)
exit(a);
writeln(' very') (*never executed*)
end; (*c*)
begin (*b*)
c;
writeln('cold ') (*never executed*)
end; (*b*)
begin (*a*)
b;
writeln('cruel') (*never executed*)
end; (*a*)
begin (*main*)
writeln('hello');
a;
writeln('world')
end. (*main*)
Notice that the statement exit(a) takes the execution back to
the point the a was called in main.
-Just My $0.02 worth
--
=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
Eric Cabot | elmo@uhura.cc.rochester.edu
"insert your face here" | elmo@uordbv.bitnet
=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=maman@uranie.inria.fr (Nathan Maman) (01/29/91)
I don't know exactly how these COMEFROM's worked, but perhaps they could be used in Exceptions|Errors|Signals treatment(s). Example: Sub s1 statements return entry-point s1_some_signal treatment you should be able here to a) return to calculation in s1 b) return to calling sub c) exit from program with some message end s1 Sub signal_handler if COME-FROM s1 then go to s1_some_signal end if return (or whatever: stop, ...) end What do you think, am I wrong ? -- Nat. +--------------------------------------------------------------------------+ | Address: M. Nathan MAMAN, INRIA Sophia-Antipolis, 06560 Valbonne, FRANCE | | E-mail: maman@mirsa.inria.fr, Phone: 33-93.65.77.95, FAX: 33-93.65.78.58 | +--------------------------------------------------------------------------+