

I write a lot of Python. I hate it when people use “X is more pythonic” as some kind of argument for what is a better solution to a problem. I also have a hang up with people acting like python has any form of type safety, instead of just embracing duck typing.This lands us at the following:
The article states that “you can check a list for emptiness in two ways: if not mylist
or if len(mylist) == 0
”. Already here, a fundamental mistake has been made: You don’t know (and shouldn’t care) whether mylist
is a list. These two checks are not different ways of doing the same thing, but two different checks altogether. The first checks whether the object is “falsey” and the second checks whether the object has a well defined length that is zero. These are two completely different checks, which often (but far from always) overlap. Embrace the duck type- type safe python is a myth.
Type hints are usually great, as long as they’re kept up to date and the IDE interprets them correctly. Recently I’ve had some problems with PyCharm acting up and insisting that matplotlib doesn’t accept numpy arrays, leading me to just disable the type checker altogether.
All in all, I’m a bit divided on type hints, because I’m unsure whether I think the (huge) value added from correct type hints outweighs the frustration I’ve experienced from incorrect type hints. Per now I’m leaning towards “type hints are good, as long as you never blindly trust them and only treat them as a coarse indicator of what some dev thought at some point.”