Hello,
On Sat, 29 May 2021 17:29:26 -0300
André Roberge <andre.robe...@gmail.com> wrote:
> On Sat, May 29, 2021 at 4:54 PM Irit Katriel <iritkatr...@yahoo.com>
> wrote:
>
> >
> > You can control what the traceback of exceptions you are emitting:
> >
> > "raise e.with_traceback(None)" should clear everything before the
> > current frame.
> >
>
> I'm sorry, but I still don't see how. This particular line would
> still show up.
>
>
> Traceback (most recent call last):
> File "test.py", line 2, in <module>
> d = date(2021, 13, 1)
> File "C:\Users\andre\local_datetime.py", line 852, in __new__
> raise e.with_traceback(None)
> ValueError: ('month must be in 1..12', 13)
>
>
> Sorry if I am missing something obvious. In the example I gave, as a
> user calling date() [from a library], I would only want to see that
> line show up.
It would be *very* confusing to see something like:
> File "some/where/deep.py", line 2123, in <module>
> foo = bar(x, *y)
> ValueError: ('month must be in 1..12', 13)
You can start your stopwatch and see how much time it will take you to
figure out that "bar" is a variable referencing "date" and sequence "y"
has "month" somewhere in it.
That already happens in CPython in some places, and it's quite
confusing when you hit it:
https://mail.python.org/archives/list/python-ideas@python.org/thread/MINLM7BBAAI44WJDHDZ2ZBHNQ4P4XCQG/
On the topic of "functions implemented in C provide clean tracebacks",
on a couple of occasions, I found them to be terse up to being
obfuscated. I really consider one sweet day to be able to implement
feature to bring them closer to Python level of user-friendliness,
e.g.
> Traceback (most recent call last):
> File "foo.py", line 2, in test
> builtin_func(a)
> File "~/projects/foo_module/src1.c", line 34, in builtin_func_impl
> ValueError("wrong phase of moon")
So it was possible to debug code across C extensions boundary more
easily (instead of grepping loads of C code for confusing/generic error
messages guessing which one was actually hit).
Oh, and btw CPython importlib also implements some traceback
obfuscation:
https://github.com/python/cpython/blob/bb3e0c240bc60fe08d332ff5955d54197f79751c/Lib/importlib/_bootstrap.py#L233
Besides user satisfaction ("clean tracebacks"), I guess it contributes
largely to the fact that only a few people know how Python import
machinery works and are able to customize it. (At least, I found it
pretty hard to work with - you literally need to go thru the entire
importlib source code and remove those pesky
_call_with_frames_removed() calls, and only then you start to get a
picture what breaks where and how it all works together).
> >
> >
> > Or you can get clever and construct a traceback with only the
> > frames you want.
> >
> >
> > On Saturday, May 29, 2021, 08:27:18 PM GMT+1, André Roberge <
> > andre.robe...@gmail.com> wrote:
> >
> > What I am interested in is having a project-agnostic standardised
> > Python way to specify what to show to an end-user when an exception
> > is raised.
> >
> >
--
Best regards,
Paul mailto:pmis...@gmail.com
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