[issue44576] AttributeError: incorrect line identified in Python 3.10

[Alex Hall]

Alex Hall <alex.mojaki at gmail.com> added the comment:

I believe this is the outcome of https://bugs.python.org/issue39316 which I filed, so I'm pulling in . Naturally I think the new behaviour is not a bug but a feature.

I think it's more important for the traceback to show the attribute access (`two`) than the value (`one`). That's what the frame was doing at the time which led to the error.

The difference becomes even more important when calling a method with no arguments. Given this script:

class A:
    def b(self):
        1 / 0


x = (
    A()
        .b()
)


The 3.9 traceback points to the line with `A()` in the `<module>` frame, while 3.10 correctly points to `.b()`, which makes the following line 'in b' make more sense.

Where the old behaviour has really gotten to me is when I run the pycharm debugger and put a breakpoint on the .b() line and it never gets hit. Not being sure what lines 'count', I sometimes defensively put breakpoints on a cluster of lines, then spend more time removing them later. Having that fixed in 3.10 is great.

----------
components: +Interpreter Core
nosy: +Mark.Shannon, alexmojaki
type:  -> behavior

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<https://bugs.python.org/issue44576>
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