Question

In the following code i am trying to implement inheritance and polymorphism properties,My question is obj1.hello3("1param","2param") obj1.hello3("11param") are these statements not correct what would be the correct way of doing this

  #!/usr/bin/python

  class test1:
     c,d = ""
     def __init__(self,n):
        self.name = n
        print self.name+"==In a"
     def hello1(self):
        print "Hello1"
     def hello3(self,a,b):
        #print "Hello3 2 param"+str(a)+str(b)
        #print "ab"+str(self.a)+str(self.b)+"Hello1"
        print "Hello3 2 param"

     def hello3(self,a):
        #print "a"+str(self.a)+"Hello1"
        print "Hello3 1 param"+str(a)

  class test2(test1):
     def __init__(self,b):
        test1.__init__(self, "new")
        self.newname = b
        print self.newname+"==In b"
     def hello2(self):
        print "Hello2"

  obj= test1("aaaa")
  obj1=test2("bbbb")
  obj1.hello1()
  obj1.hello2()
  obj1.hello3("1param","2param")
  obj1.hello3("11param")

Answer 1

You are trying to implement method overloading rather than inheritance and polymorphism.

Python does not support overloading in the way that C++, Java, C# etc. do. Instead, to achieve what you want in Python, you need to use optional parameters.

def hello3(self,a,b=None):
    if b is None:
        print "Hello3 1 param", a
    else:
        print "Hello3 2 param", a, b

...

obj1.hello3("a")#passes None for b param
obj1.hello3("a", "b")