大约有 46,000 项符合查询结果（耗时：0.0452秒） [XML]
Should I implement __ne__ in terms of __eq__ in Python?
I have a class where I want to override the __eq__ method. It seems to make sense that I should override the __ne__ method as well, but does it make sense to implement __ne__ in terms of __eq__ as such?
...
How to properly assert that an exception gets raised in pytest?
...Exception) is what you need.
Code
import pytest
def test_passes():
with pytest.raises(Exception) as e_info:
x = 1 / 0
def test_passes_without_info():
with pytest.raises(Exception):
x = 1 / 0
def test_fails():
with pytest.raises(Exception) as e_info:
x = 1 / 1...
A simple explanation of Naive Bayes Classification
I am finding it hard to understand the process of Naive Bayes, and I was wondering if someone could explain it with a simple step by step process in English. I understand it takes comparisons by times occurred as a probability, but I have no idea how the training data is related to the actual datase...
C++ preprocessor __VA_ARGS__ number of arguments
...variadic argument macros, how to find the number of arguments? I am okay with boost preprocessor, if it has the solution.
...
What does if __name__ == “__main__”: do?
...
Whenever the Python interpreter reads a source file, it does two things:
it sets a few special variables like __name__, and then
it executes all of the code found in the file.
Let's see how this works and how it relates to your question about the __name__ checks we always s...
Usage of __slots__?
What is the purpose of __slots__ in Python — especially with respect to when I would want to use it, and when not?
11 A...
Can someone explain __all__ in Python?
...e and more, and I keep seeing the variable __all__ set in different __init__.py files. Can someone explain what this does?
...
Difference between __getattr__ vs __getattribute__
...__getattr__ is only invoked if the attribute wasn't found the usual ways. It's good for implementing a fallback for missing attributes, and is probably the one of two you want.
__getattribute__ is invoked before looking at the actual attributes on the object, and so can be tricky to implement corr...
How to “perfectly” override a dict?
...
You can write an object that behaves like a dict quite easily with ABCs (Abstract Base Classes) from the collections.abc module. It even tells you if you missed a method, so below is the minimal version that shuts the ABC up.
from co...
What are metaclasses in Python?
...es. A class is an instance of a metaclass.
While in Python you can use arbitrary callables for metaclasses (like Jerub shows), the better approach is to make it an actual class itself. type is the usual metaclass in Python. type is itself a class, and it is its own type. You won't be able to recrea...