I actually like it if a language lets you spell out your intention, although
adding many keywords is not a plus.
So, yes something like:
loop
...
end loop;
Is appealing as it makes clear the decision on when to exit the loop must be
within the loop (or till something kills ...)
In languages like C/C++ there are people who make up macros like:
#define INDEFINITELY_LOOP while (true)
Or something like that and then allow the preprocessor to replace
INDEFINITELY_LOOP with valid C code.
So, how to do something like that in python, is a challenge left to the user 😉
Bottom line I find is it is a great idea to write comments as even if you are
the one reviewing the code much later, you may struggle to figure out what you
did and why.
-----Original Message-----
From: Python-list <python-list-bounces+avigross=verizon....@python.org> On
Behalf Of Dennis Lee Bieber
Sent: Sunday, September 5, 2021 12:50 PM
To: python-list@python.org
Subject: Re: on writing a while loop for rolling two dice
On Sat, 4 Sep 2021 12:27:55 -0500, "Michael F. Stemper"
<michael.stem...@gmail.com> declaimed the following:
>
>Kernighan and Ritchie agree(d) with you. Per _The C Programming
>Language__:
> Experience shows that do-while is much less used that while
> and for.
>
And just for confusion, consider languages with "repeat / until"...
"do / while" repeats so long as the condition evaluates to "true";
"repeat / until" /exits/ when the condition evaluates to "true".
Then... there is Ada...
While one is most likely to encounter constructs:
for ix in start..end loop
...
end loop;
and
while condition loop
...
end loop;
the core construct is just a bare
loop
...
end loop;
which, with the "exit when condition" statement allows low-level emulation of
any loop... (same as Python "if condition: break"
loop -- "while" loop
exit when not condition;
...
end loop;
loop -- "repeat / until"
...
exit when condition;
end loop;
loop -- split
...
exit when condition;
...
end loop;
{I'm not going to do the "for" loop, but one can easily manage
initialization/increment/test statements}.
To really get your mind blown, look at loops in REXX...
do while condition
...
end
do until condition
/* note that the termination parameter is listed at top, */
/* but takes effect at the bottom, so always one pass */
...
end
do forever
...
if condition then
leave
...
end
do idx = start to end /* optional: by increment */
...
end
do idx = 1 by increment for repetitions
...
end
AND worse! You can combine them...
do idx = start for repetitions while condition1 until condition2
...
end
{I need to check if both while and until can be in the same statement}
--
Wulfraed Dennis Lee Bieber AF6VN
wlfr...@ix.netcom.com http://wlfraed.microdiversity.freeddns.org/
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