What is the difference between "is None" and "== None" What is the difference between "is None" and "== None" python python

What is the difference between "is None" and "== None"


The answer is explained here.

To quote:

A class is free to implement comparison any way it chooses, and it can choose to make comparison against None mean something (which actually makes sense; if someone told you to implement the None object from scratch, how else would you get it to compare True against itself?).

Practically-speaking, there is not much difference since custom comparison operators are rare. But you should use is None as a general rule.


class Foo:    def __eq__(self,other):        return Truefoo=Foo()print(foo==None)# Trueprint(foo is None)# False


In this case, they are the same. None is a singleton object (there only ever exists one None).

is checks to see if the object is the same object, while == just checks if they are equivalent.

For example:

p = [1]q = [1]p is q # False because they are not the same actual objectp == q # True because they are equivalent

But since there is only one None, they will always be the same, and is will return True.

p = Noneq = Nonep is q # True because they are both pointing to the same "None"


matomo