Port implementation from loguru PR

[kornicameister]

Original PR: Delgan/loguru#276

[kornicameister]

@Delgan I will move include corner cases in this or in another PR. I'd like to get your opinion on this PR first if you have time and don't mind :)

[kornicameister]

from loguru import logger

def foo(a, b):
    a / b

try:
    foo(1, 0)
except Exception:
    logger.exception("An error occurred while executing: '{}'", foo)

Ok, I understand why this shouldn't be evaluated as an error. Point made, but this actually complicates things. Correct me, but would doing logger.opt(lazy=True).exception(...) actually tried to call foo?

[Delgan]

Well, you know a lot more about mypy plugins than I do, so I don't have much useful to add. I'm learning a lot thanks to your PR. 😁

It looks good. We can improve it gradually afterwards anyway.

[Delgan]

Ok, I understand why this shouldn't be evaluated as an error. Point made, but this actually complicates things. Correct me, but would doing logger.opt(lazy=True).exception(...) actually tried to call foo?

Indeed, there are a lot of special cases that can make things complicated. 😁

I'm not sure fixing this worth the trouble. It was just to give an example of the limitations we were going to face. There exist probably other edge cases of that kind, unfortunately.

A false positive is more critical than a false negative, though.

I don't know how this can be corrected. Surely we should introspect the internal attributes of the logger, if that is possible.

Your description of the lazy parameter is absolutely correct. If set to True, the logging arguments will be called and returned value will be used for the formatting. If set to False (the default), the argument could be of any type and will be formatted as is (including a function which will not be called in this case).

[kornicameister]

@Delgan I've created an issue #6 to approach lazy={true,false} later on.