Calling a base class method from a derived class method in Python

Question

I have a class A and I have inherited a class B from class A. I have two methods methodX & methodY in ClassA. This methodY will be calling methodX in classA. Now I have a methodZ in ClassB.

The following is the scenario:-

class A(object):
 def methodX(self):
  ....
 def methodY(self):
  methodX()

class B(A)
 def methodZ(self):
  self.methodY() #says the global methodX is not defined

My question is that I have to call methodY which inturn calls methodX from methodZ. How is it possible? Should I define the methodX globally ? Or is there any other alternative.. Thanks in advance !

detly · Accepted Answer · 2013-04-02 05:51:19Z

3

In methodY you should be calling self.methodX().

answered Apr 2, 2013 at 5:51

detly

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4 Comments

a4aravind Over a year ago

Sorry..That was a typo here. I have called it in the same manner only: self.methodX().

Daniel Roseman Over a year ago

@user2234700 If that was true, you wouldn't have got the "global name" error. Please post your actual code.

a4aravind Over a year ago

@DanielRoseman Actually the methodX() I've reffered here is an event handler and I'm calling that in methodY(). It's a Sikuli code.The method call from methodY() goes like this : onChange(10,methodX) where methodX() is the eventhandler

detly Over a year ago

@user2234700 - If that's the case I'd say there's something else going on with your code outside of the snippet you posted.

user2194299 · Accepted Answer · 2013-04-02 08:45:42Z

0

As it has been said before, using self.methodX() seems to be solving your problem. Check this:

class A(object):
    def methodX(self):
        print "A.methodX"
    def methodY(self):
        print "A.methodY"
        self.methodX()

class B(A):
    def methodZ(self):
        print "B.methodZ"
        self.methodY()

b = B()
b.methodZ()

Generates this output:

$ python test.py
B.methodZ
A.methodY
A.methodX
$

Which I think it's what you were looking for...

answered Apr 2, 2013 at 8:45

user2194299

Comments

Aswin Murugesh · Accepted Answer · 2013-04-02 07:35:43Z

0

Since a member function cannot be called without using the object of that class, this error is thrown. Using

self.methodX()

Calls the function methodX() using the object using the object used to call the methodY()

answered Apr 2, 2013 at 7:35

Aswin Murugesh

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