Python subclassing explained

subclasses.md

1. Case1:

   Define Base.init(self)

class Base(object):
    def __init__(self):
        self.anattribute = 23
class Derived(Base):
    def __init__(self):
        Base.__init__(self)
        self.anotherattribute = 45

# Expect 23 here as an output
Derived().anattribute
# 23

2. Case2: Don't define Base.init(self)

class Base(object):
    def __init__(self):
        self.anattribute = 23
class Derived(Base):
    def __init__(self):
        self.anotherattribute = 45

# Expect an exception here
Derived().anattribute

3. Case3:

   Don't define Derived.init(self)

class Base(object):
    def __init__(self):
        self.anattribute = 23
class Derived(Base):
    pass

# Didn't define __init__ so automatically Base.__init__.py will be called
Derived().anattribute