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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: Why C++ is successful
Date: 1998/08/14
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Date: 1998-08-14T00:00:00+00:00
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Andy said

<<Ahh... but have you ever found a "good" reason for using it? I have used
goto in C and Pascal in certain rare cases, but I have always found clearer
ways to code these cases in Ada.
>>

The two obvious uses vfor gotos in Ada are

1) to get a loop "continue" mechanism

2) to write finite state machines encoding the state into the PC. Yes, some
people prefer case statements for this purpose, but many people prefer the
use of labels and gotos as the most obvious translation of labeled states
with arrows between them.

In general, the use of gotos makes sense if the resulting code is clearer
and easier to maintain. THat's relatively rare, but not non-existnent, and
it is quite common to run across tortured code with multiple boolean flags
which can be easily simplified using a goto. 

For example, I find the following perfectly clear:

   <<sort>> for J in 1 .. N - 1 loop
       if D (J) > D (J + 1) then
	  Swap (D(J), D(J + 1));
          goto Sort;
       end if;

It is a little tricky to program this without the goto and not make it
less clear. Actuallky many people who try this end up with a different
algorithm (hint: the above sort is cubic, it is NOT a quadratic bubble sort :-)
dp