Python Class inheritance trouble

Question

When I try to do this I get the error NameError: global name 'name' is not defined is there an easy work around?

class C(object): 
 def __init__(self, name): 
 self.name = name
class D(C): 
 def __init__(self): 
 C.__init__(self, name)
obj1 = D() 

• hongsy: hi and welcome to SO! this looks like homework. please read asking about homework and edit your question if required.
• hongsy: C.__init__(self, name) <- this line is the issue. where is name coming from in class D():?

Answer 1

In class D, when you initialize it from C, you're not passing a value to the initialization of C, so it raises a NameError when it tries to pass it. You either need to allow D to take a value name and then pass it to C,

class C(object):
 def __init__(self, name):
 self.name = name
class D(C):
 def __init__(self, name):
 C.__init__(self, name) # name must be passed on initialization of D.

or define a default value for name in D.

class C(object):
 def __init__(self, name):
 self.name = name
class D(C):
 def __init__(self, name='Monty Python'):
 C.__init__(self, name) # allows you to only pass a name if you want to.

Answer 2

Instead of using the parent class name use super() here so that later if you need to you can enable things like mixins, interfaces, abstract classes, etc.

Then you can also allow for those keyword arguments in the parent class to be used in the child class like this:

class D(C):
 def __init__(self,**kwargs):
 super(D,self).__init__(**kwargs)

Example usage:

In [349]: obj1 = D(name='test') 
In [350]: obj1.name 
Out[350]: 'test'

• i_am_deesh: you don't have to give arguments to super() by default it will take the class.
• mechanical_meat: I understand that. I left it this way to be clearer to someone learning the language.

Answer 3

never ever hard code the metho you inheriting instead of do super() by this if you want to change the method just change in the class name will be sufficient

there is no need to give argument's to super() in python3

 class C(object):
 def __init__(self, name):
 self.name = name
 class D(C):
 def __init__(self, name):
 super().__init__(self, name)