On Tue, 22 Apr 2008 18:18:14 -0500, Patrick O'Keefe wrote:
>On Tue, 22 Apr 2008 22:41:49 +0000, Ted MacNEIL
><[EMAIL PROTECTED]> wrote:
>
>>>I think abuse of ITERATE and LEAVE to be a much milder crime.
>>
>>I don't know what you mean by abuse, but when I studied
>modular/structured programming at the University of Waterloo, these
>were considered valid constructs.
>>...
>
>I absolutely agree. Even when absolutes aren't appropriate.
>
Consider:
/* I do this all the time... */
do phonyblock = 1 for 1
...
if Bailout then leave phonyblock
...
end phonyblock
o I put a "name = 1 for 1" on all my large blocks, and use a
matching "end name"
- the interpreter checks that my "end"s match my "do"s.
- but it's a kludge because I can't name the "end" nor the
"leave" without introducing a phony control variable.
- but using "leave" insted of "signal" allows me to nest
it all within a larger block.
o I always put a name on the "leave" and "iterate", even when
they refer to then innermost block (and I have no qualms
about multi-level "iterate" and "leave", which are possible
if one names the control variable).
- It's documentation.
- It protects against unexpected results if one introduces
another inner nesting level.
You're entitled to say that if I'm doing that, I should modularize
to smaller blocks.
I can see where someone not expecting this could consider it
"leave" abuse.
>I may have misunderstood Paul, but I assume he was describing
>such convoluted logic that use of SIGNAL might have actually
>made more understandable code. I was trying to say the even then
>I would consider use of ITERATE and LEAVE preferable to SIGNAL.
>
Where I'd code:
if X then do
call B
call C
end; else do
call A
call C
end
My nemesis has coded:
if X then signal B
A: /* unnecessary label for comparison with above. */
/* some stuff */
signal C
B:
/* some other stuff */
C:
/* final stuff */
... perhaps all within a loop that needs to be implemented with
SIGNAL because of the interior SIGNALs.
>In fact, I'm not sure that I would ever use SIGNAL to break out of a
>complex nested loop structure even if it DID greatly simplify the
>logic. In fact, I don't even like named LEAVE; I leave each level
>seperately. (And that is probably even more pig-headed than
>religiously avoiding SIGNAL.)
>
But you have to do that with CALLs. There's no construct for
leaving multiply nested procedures. Except for my nemesis's
using SIGNAL until the stack overflows.
-- gil
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