Replace asserts with exceptions #5494
Description
🚀 The feature
I propose to replace most asserts that we find in TorchVision with an if-statement -> exception clause.
There are two patterns that I think could be modified:
Checking input types
assert isinstance(x, MyType)can be replaced by
if not isinstance(x, MyType):
raise TypeError(f"This function/method expects x of type MyType, instead got {type(x}")Checking for input values
assert x >= 0can be replaced by
if x < 0:
rase ValueError("x should be greater or equal to 0")These changes should be done in cases where it is important to stop the normal flow and perhaps handle the exception in a particular manner. Otherwise, in my opinion, we should just use the type hints as we currently do and follow the general duck typing principle in python (so no assert or exceptions needed).
If this is implemented the test asserts should stay, the documentation (development documentation) should be updated with a note about best practices, and other kinds of asserts and corresponding replacements should be considered.
Motivation, pitch
Asserts do not run when we execute the python in the optimised mode, so when they perform important checks we should throw exceptions instead. If the checks are not important we can just follow the duck typing principle in python.
Alternatives
No response
Additional context
No response