Question

This is my code:

class bla:
    def function1():
        print 1
    def function2():
        bla.function1()

x = bla()

x.function2()

I don’t understand why I get the error “TypeError: function2() takes no arguments (1 given)” as I don’t seem to be passing any argument to function2.

Answer 1

Regular methods are called with an implicit self reference to their object – otherwise they wouldn’t be able to access any data members of x.

They should always be declared like so:

class bla:
    def function1(self):
        print 1

if you want them to operate on the object (self is loosely equivalent to the this pointer in C++, for example).

Alternatively, if you don’t care about the object (so you’re really just using the class to group some functions together), you can make them static like so:

class bla:
    @staticmethod
    def function1():
        print 1

    @staticmethod
    def function2():
        bla.function1()

In fact, that’s the only way you can call bla.function1() without an instance of bla from your function2.