Both Google and Python's style guide is the best practice: if x is not None: # Do something about x. Using not x can cause unwanted results. ... <看更多>

Python uses the keyword None to define null objects and variables. While None does serve some of the same purposes as null in other ... ... <看更多>

None is a singleton object, comparing using == invokes the __eq__ method on the object in question, which may be slower than identity comparison. Comparing to ... ... <看更多>

Always use if foo is None: (or is not None ) to check for a None value. E.g., when testing whether a variable or argument that defaults to None was set to some ... ... <看更多>

Well, method resolution order in Python (also applicable to data members) is not very simple. What is not found on instance level, will be ... ... <看更多>