Trying to understand nested loops

[avi.e.gross at gmail.com]

This reminds me a bit of how routine spelling checkers and often especially
grammar checkers, generate so many suggestions about mistakes as to become
ignored. If you are writing using lots of names and jargon that keep getting
flagged as errors and they are spelled or used exactly as you want, then it
gets to be too annoying and you turn off the feature. Yes, you can sometimes
silence some things in a spell checker that allows you to add words to a
custom dictionary but for now, that dictionary is not known to every
application that checks your spelling.

That can be the nature of the beast. If your compiler decides to warn you
every time you do a division that you might be dividing by zero because you
do not perform the test right before that, then you end up with code that
tests it AGAIN after having arranged for the value to never be zero in the
first place, then test it again when you divide something else by it, ...

I am sure some programming language has some kind of pragma that lets you
whisper to the compiler that this variable at this time is guaranteed not to
be zero, or that the region is in a try/catch zone which will intercept and
fix the results of a divide by zero error.

Just an example. And as you say, new or improved compilers can be made to be
ever more picky about trying to find possible anomalies.

Things are useful when they are somewhat manageable. If a compiler things it
detects 372 places in your code where the same thing needs to be mentioned,
such as reserving space for an object without simultaneously filling it with
some contents, then it would be nice if instead of printing ALL of them, it
consolidated it into one warning and say you can click on something to see
the 372 instances. 

-----Original Message-----
From: Python-list <python-list-bounces+avi.e.gross=gmail.com at python.org> On
Behalf Of Chris Angelico
Sent: Saturday, August 6, 2022 8:12 AM
To: python-list at python.org
Subject: Re: Trying to understand nested loops

On Sat, 6 Aug 2022 at 22:08, Richard Damon <Richard at damon-family.org> wrote:
>
> On 8/6/22 12:01 AM, Chris Angelico wrote:
> > On Sat, 6 Aug 2022 at 13:54, Dan Stromberg <drsalists at gmail.com> wrote:
> >> On Fri, Aug 5, 2022 at 12:54 PM Grant Edwards 
> >> <grant.b.edwards at gmail.com>
> >> wrote:
> >>
> >>> In C, this doesn't do what it looks like it's supposed to do.
> >>>
> >>>     if (foo)
> >>>       do_this();
> >>>       and_this();
> >>>     then_do_this();
> >>>
> >> It's been quite a while since I used C, but with the right compiler 
> >> flag(s), I think this may be a thing of the past when compiling with
gcc:
> >> https://developers.redhat.com/blog/2016/02/26/gcc-6-wmisleading-ind
> >> entation-vs-goto-fail
> > Ah yes, because compiler warnings are always viewed and acted upon.
> >
> > Have you ever watched the compilation of a large open-source 
> > project, done using the project's own build system and therefore the 
> > team's preferred warning settings? It's normal to have such a spew 
> > of warnings that you can't find anything interesting, or to have new 
> > warnings in new versions of GCC be utterly useless for the same 
> > reason.
> >
> > ChrisA
>
> You make it so you HAVE to fix the warning by adding the option to 
> make warnings into errors.
>
> This does mean that you need to fix all the warnings that don't 
> actually mean anything,
>
> Good code shouldn't generate many warnings, either you have warnings 
> enabled that you don't care about, or your code is doing things you 
> have told the complier you shouldn't do.
>

I say again: have you ever watched the compilation of a large open-source
project? You cannot turn warnings into errors, because there are ALWAYS
warnings. Maybe, once upon a time, the policy was to ensure that there were
no warnings on any major compiler; but times change, compilers add new
warnings, new compilers join the club, and it becomes practically impossible
to prevent warnings. Which, in turn, makes all warnings basically
meaningless.

Hmm. I don't think I've ever compiled gcc from source. Maybe I should do
that, just to see whether gcc itself compiles with no warnings under gcc.

ChrisA
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