Inner class function without self

Question

Peace, everyone! I\'m using Python 3.6.3 and I find strange that such construction is possible:

class TestClass(object):
    def __init__(self):
        self         


        

Answer 1

TestClass.test() call actually executes the test() on the class object. This is similar to a @staticmethod (a method that can be executed on the class object, without creating an object first).

ins = TestClass()
ins.test()

will throw an exception, since instance methods pass self as the first argument, and test() takes no args.

When an object is created, the methods defined in the clas are bound to it. They are actually different objects, hence they have different ids:

   id(TestClass.test)
=> 140288592901800
   obj = TestClass()
   id(obj.test)
=> 140288605765960

In Python 2.7, your code throws an exception which is self explantory:

Traceback (most recent call last):
  File "", line 1, in 
    TestClass.test()
TypeError: unbound method test() must be called with TestClass instance as 
first argument (got nothing instead)