nameerror - function name is undefined in python class

21
votes

I am relatively new to python and i am experiencing some issues with namespacing.

class a:
    def abc(self):
        print "haha" 
    def test(self):
        abc()

b = a()
b.test() #throws an error of abc is not defined. cannot explain why is this so
2
pythonnameerror
It is working, the function abc() of class a is called by its instance. - Vivek Sable
I think instead of b.abc(), yours call to b.test() should be throwing the error. And that's because you should be calling abc() with the reference of the class instance. Simply replace abc() with self.abc() in test() function of class a. - Anonymous

2 Answers

43
votes

Since test() doesn't know who is abc, that msg NameError: global name 'abc' is not defined you see should happen when you invoke b.test() (calling b.abc() is fine), change it to:

class a:
    def abc(self):
        print "haha" 
    def test(self):
        self.abc()  
        # abc()

b = a()
b.abc() #  'haha' is printed
b.test() # 'haha' is printed
21
votes

In order to call method from the same class, you need the self keyword.

class a:
    def abc(self):
        print "haha" 
    def test(self):
        self.abc() // will look for abc method in 'a' class

Without the self keyword, python is looking for the abc method in the global scope, that is why you are getting this error.