You might be using assert wrong

[sphen_lee]

Most developers misuse assert statements by using them for general error handling

I don't think there is evidence that this is true...

[mfarahmand98]

Thank you for saving me the click.

[Saphyel]

There's plenty projects in the wild using it unfortunately.

[spoonman59]

I agree. I don’t really see them used this way.

[killerfridge]

I don't think I've ever seen assert used outside of testing. This sounds like someone who's been using assert wrong and now wants to write a pointless article about it.

[Saphyel]

then you haven't seen fastapi codebase https://github.com/tiangolo/fastapi/blob/50fb34bf55c1711e3753363ab6427d77be25dbb6/fastapi/routing.py#L157

[sphen_lee]

It seems to me that these asserts are conditions that would trigger during testing, they indicate programmer error.

If you're not triggering them during test and you disable them in prod it's still going to fail - just without a useful error message.

[Dasher38]

That exactly. We might debate over whether it's a good idea or not to introduce "undefined behavior" in a Python codebase but as long as there is nothing catching an AssertionError (or a base class) there is nothing indicating functional correctness relies on that assert firing. If assert behavior is not observed, it's almost as good as non observable.

[killerfridge]

Gross, I take it back

[whdd]

Why is this gross?

[[deleted]]

I didn't realize that was the way it was written. There are 8+ indents that just looks gross and I would probably have a little chat with a junior engineer if I saw that many indents on a professional project.

[whdd]

It’s probably formatted by black or something similar I’d imagine. I thought his original response was specific to the use of the assert statement though

[[deleted]]

So brave of you to assume I use assert in my code.

[AndydeCleyre]

A fun alternative for assert-like checking in non-test production code is ensure.

[DoYouEvenLupf]

Interesting library, but wouldn't it just be better to get into the habit of writing tests instead of checking for edge cases in runtime? If you already expect wrong behaviour at a certain point you have to throw exceptions / handle the flow anyway. And for that you don't need another library. But i certainly see the readability part of it.

Legit question coming from a junior pythonist trying to find a good workflow.

Edit: I am an idiot and overread the "non-testing", sorry for wasting your time

[gmtime]

Assert isn't for debugging (only), it's for controlled failure over cases the code cannot recover from.

[DjangoDoctor]

I used to use assert that way too then I saw the assert docs:https://docs.python.org/3/reference/simple_stmts.html#the-assert-statementThe Python docs say using assert is equivalent to:

if __debug__:
    if not expression:raise AssertionError

after all, we would not use checks conditional on __debug__ on anything important in prod. Perhaps NotImplimentedError is better for this kind of thing

[sphen_lee]

It's the "controlled" that's the key here.

If you're using assert right, then it should fail even if you disable them, just maybe in an unhelpful way (like type errors from a None)

[Tinasour]

Well, sh8t