I'm confused about some examples I've seen of initializing classes using inheritance. Some of them look like:
class Foo(Bar):
def __init__(self, arg, parent = None):
Bar.__init__(self, parent)
self.Baz = arg
etc.
While others are simpler:
class Foo(Bar):
def __init__(self, arg):
Bar.__init__(self)
etc.
What is the purpose of using a "parent" argument to __init__?
Generally passing parent is not something that's required, only when the parent class's constructor explicitly needs such an argument. This is used in some hierarchies, such as PyQt.
And a good idiom of parent class initialization is to use super:
class Child(Father):
def __init__(self):
super(Child, self).__init__()
super() only works with new-style classes in Python 2, or Python 3. It doesn't work with old-style classes in Python 2. Make sure your base class is a new-style class (inherits from object).
In your example the variable "parent" is misleading. Simply the parent class COULD require additional arguments that must be provided
class Pet:
def __init__(self,name):
self.name = name
class Dog(Pet):
def __init__(self,name,age):
Pet.__init__(self,name)
self.age = age
In this example the parent class Pet requires an attribute (name), and the child class provides it
As pointed out, use "super" syntax to call parent classes methods
