Re: Software landmines (loops)

[adam@irvine.com]

In article <35F252DD.5187538@earthlink.net>,
  Charles Hixson <charleshixsn@earthlink.net> wrote:

> I suppose that it is possible to write spaghetti code without using
> goto's, I've never tried.

Sigh . . . does anyone *try* to write spaghetti code?  The thing is, someone
who's inexperienced and hasn't read enough code to know whether code is
readable or not, is certainly capable of writing unreadable, convoluted code
without using GOTO.  I can't say whether I've written any such code (because
if I did, I would have been too inexperienced to recognize it...), but I do
know that I've *seen* plenty of convoluted code written by people brought up
in the "GOTO is evil" religion.  Maybe it shouldn't be called "spaghetti
code" since the control doesn't wind up over itself; maybe "rotini code" is
more appropriate since although the different parts aren't entangled, they're
all completely twisted within themselves.  But if the goal is to write code
that doesn't give  a migraine to someone who tries to understand it, rather
than merely to identify which form of pasta is appropriate to a particular
piece of code, then Joe is absolutely right that it's possible to write code
without GOTO that is just as twisted as the unstructured, GOTO-loaded code
that older programmers used to write.

> I do know that with goto's INSTEAD OF while,
> until, elsif, begin...end, etc. it was very difficult NOT to write
> spaghetti code

How could it be that difficult?  I found it quite easy.  I used to work in
COBOL in the late 1970's, before COBOL had decent control structures, and I
learned that in many cases, it seemed better to *avoid* PERFORM .. WHILE,
since it took important chunks of code out-of-line and made it more difficult
for readers to understand.  So, instead of PERFORM..WHILE, I often wrote code
like

    START-OF-LOOP.
        IF some-condition THEN GOTO LOOP-END.
    BODY-OF-LOOP.
        ... do whatever
        GOTO START-OF-LOOP.
    LOOP-END.

(Usually with more appropriate paragraph names.)  This is well-structured, and
not difficult to write, and should be easy enough to understand for anyone who
has a clue what WHILE loops do in the first place.  So I can't imagine what
would merit calling this "spaghetti code", unless you belong to the
"GOTO-Is-Evil" religion (St. Edsger's Church) and believe that spaghettiness
can be determined by counting the number of GOTO's.

> and since there was originally the theory said that the
> best code economized on the number of CPU cycles, rather than optimized
> intelligibility, there was every reason TO write code that took
> short-cuts.

Ummm, I don't see how this has anything to do with Joe's point.  Sure, if
you think GOTO's are fine *AND* one of your prime motivations is to eliminate
as many cycles as possible, you're more likely to write unintelligible code;
but Joe is only questioning the assumption about GOTO's, and is saying nothing
whatsoever about nanosecond-squeezing code.

				-- Adam

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