Re: Loops (was Re: do { quit; } else { })

bart <bc@freeuk.com> writes:

On 20/04/2025 23:36, Keith Thompson wrote:

bart <bc@freeuk.com> writes:

>

     for(p=sqliteHashFirst(&pSchema->trigHash); p; p=sqliteHashNext(p)){
         sqlite3DeleteTrigger(db, (Trigger*)sqliteHashData(p));
     }

>

I might write it like this:
     for ( p = sqliteHashFirst(&pSchema->trigHash);
           p != NULL;
           p = sqliteHashNext(p) )
     {
         sqlite3DeleteTrigger(db, (Trigger*)sqliteHashData(p));
     }

>

I have certain preferences (spaces around most operators, explicit
comparison to NULL, willingness to split long lines) that other C
programmers may or may not share.

>
I rarely see complex loops split over multiple lines (mainly when they
get so long that they'd overflow the line, but they can still be
complex enough before then).
>
But the thing is, once you split it into multiple lines, then there is
little advantage over using a regular 'while' loop:
>
      p = sqliteHashFirst(&pSchema->trigHash);
      while (p != NULL)
      {
          sqlite3DeleteTrigger(db, (Trigger*)sqliteHashData(p));
          p = sqliteHashNext(p) )
      }

You prefer a while loop.  That's a perfectly valid preference,
one that you've repeated so often that it's **boring**.  I still
like the for loop.

[...]

AFAIK it is legal C code, and I invented it because somebody said
things that belong together should be together in one place. However,
I have seen actual examples like that, in for-headers that that use
comma-separated expressions.

I also have seen C for loops written in ways I don't like.

I'd rather not write `for (ch in 0..255)` because it's a syntax error.

>
It's a syntax error because the form doesn't naturally exist in C;
you'd have to emulate using macros, which is a poor solution.

Yes.

You have the luxury of using your own language.

>
That 'ch in 0..255' form or close equivalent is supported by that long
set of languages I listed earlier. It's not my invention, I just
copied it.
>
It is just something that is desirable. Look again at the C version:
it looks off. (At least, you'd use a shorter loop index!)

It's something that *you* desire, which is perfectly fine.  And the fact
that others don't desire it seems to deeply offend you, which is weird.

I said I tried one like C's, and it was never used. There is enough
flexibility in the rest to deal with anything that comes up.

It was never used by whom?

>
By me. One use-case was porting code from C, but I didn't do much of
that either.
>

If you don't like C-style for loop, they absolutely should not
exist in a language for which you are, if I understand correctly,
the sole implementer and the sole user.

>
But I hear so much about how wonderful it is, how multi-purpose, how
indispensible, how superior to an ordinary 'for' (admittedly from
people who don't have a choice) that I didn't want to miss out!

Again, stop misrepresenting what other people say.

Wonderful?  No, I don't recall anyone other than you using that word,
and only sarcastically.

Multi-purpose?  Yes, absolutely.

Indispensible?  No, I don't believe anyone has made that claim, and it
would be inaccurate.

Superior to an ordinary 'for'?  Certainly a lot of people think it is,
because of its flexibility.  (And I could argue that C-style for loops
*are* "ordinary", since a number of languages have adopted them, but I
won't, because it would be an argument about the precise meaning of
"ordinary", which is both off-topic and not something I care about.)

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */