Why doesn't Python (error msg) tell me WHAT the actual (arg) values are ?

[Weatherby,Gerard]

“So the case where the assumption fails may not be easily
reproducable and the more information you can get post-mortem the
better”

That’s true for rare corner cases or esoteric race conditions. Usually, when I see asserts it's just because I was just plain stupid.

From: Python-list <python-list-bounces+gweatherby=uchc.edu at python.org> on behalf of Peter J. Holzer <hjp-python at hjp.at>
Date: Saturday, February 25, 2023 at 5:21 PM
To: python-list at python.org <python-list at python.org>
Subject: Re: Why doesn't Python (error msg) tell me WHAT the actual (arg) values are ?
On 2023-02-25 21:58:18 +0000, Weatherby,Gerard wrote:
> I only use asserts for things I know to be true.

Yeah, that's what assers are for. Or rather for things that you *think*
are true.

> In other words, a failing assert means I have a hole in my program
> logic.

Yes, if you include your assumptions in your definition of "logic".


> For that use, the default behavior –telling me which line the assert
> is on, is more than sufficient. Depending on the circumstance, I’ll
> re-run the code with a breakpoint or replace the assert with an
> informative f-string Exception.

That may not always be practical. Things that we know (or think) are
true often have *are* true in most cases (otherwise we wouldn't think
so). So the case where the assumption fails may not be easily
reproducable and the more information you can get post-mortem the
better. For example, in C on Linux a failed assertion causes a core
dump. So you can inspect the complete state of the program.

        hp

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