Private methods in Python

I would like to have a function in my class, which I am going to use only inside methods of this class. I will not call it outside the implementations of these methods. In C++, I would use a method declared in the private section of the class. What is the best way to implement such a function in Python?

I am thinking of using a static decorator for this case. Can I use a function without any decorators and the self word?

Solution

Python doesn't have the concept of private methods or attributes. It's all about how you implement your class. But you can use pseudo-private variables (name mangling); any variable preceded by __(two underscores) becomes a pseudo-private variable.

From the documentation:

Since there is a valid use-case for class-private members (namely to avoid name clashes of names with names defined by subclasses), there is limited support for such a mechanism, called name mangling. Any identifier of the form __spam (at least two leading underscores, at most one trailing underscore) is textually replaced with _classname__spam, where classname is the current class name with leading underscore(s) stripped. This mangling is done without regard to the syntactic position of the identifier, as long as it occurs within the definition of a class.

class A:
    def __private(self):
       pass

So __private now actually becomes _A__private.

Example of a static method:

>>> class A:
...     @staticmethod         # Not required in Python 3.x
...     def __private():
...         print 'hello'
...
>>> A._A__private()
hello