Python How do I make a subclass from a superclass

Question

In Python  how do you make a subclass from a superclass

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There is another way to make subclasses in python dynamically with a function type():

SubClass = type('SubClass', (BaseClass,), {'set_x': set_x})  # Methods can be set, including __init__()

You usually want to use this method when working with metaclasses. When you want to do some lower level automations, that alters way how python creates class. Most likely you will not ever need to do it in this way, but when you do, than you already will know what you are doing.

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class Mammal object     mammal stuff  class Dog Mammal     doggie stuff

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Initialize using Parent   class MySubClass MySuperClass       def   init   self           MySuperClass   init   self    Or  even better  the use of Python s built-in function  super    see the Python 2 Python 3 documentation for it  may be a slightly better method of calling the parent for initialization     Better initialize using Parent  less redundant     class MySubClassBetter MySuperClass       def   init   self           super MySubClassBetter  self    init       Or  same exact thing as just above  except using the zero argument form of super    which only works inside a class definition    class MySubClassBetter MySuperClass       def   init   self           super     init

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class Subclass  SuperClass           Subclass stuff here

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A heroic little example   class SuperHero object    superclass  inherits from default object     def getName self           raise NotImplementedError  you want to override this on the child classes  class SuperMan SuperHero    subclass  inherits from SuperHero     def getName self           return  Clark Kent   class SuperManII SuperHero    another subclass     def getName self          return  Clark Kent  Jr    if   name         main         sm   SuperMan       print sm getName       sm2   SuperManII       print sm2 getName

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class MySubClass MySuperClass       def   init   self           MySuperClass   init   self              lt the rest of your custom initialization code goes here gt    The section on inheritance in the python documentation explains it in more detail

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In the answers above  the super is initialized without any  keyword  arguments  Often  however  you would like to do that  as well as pass on some  custom  arguments of your own  Here is an example which illustrates this use case   class SortedList list       def   init   self   args  reverse False    kwargs           super     init    args    kwargs          Initialize the super class         self reverse   reverse         self sort reverse self reverse            Do additional things with the custom keyword arguments   This is a subclass of list which  when initialized  immediately sorts itself in the direction specified by the reverse keyword argument  as the following tests illustrate   import pytest  def test 1        assert SortedList  5  2  3       2  3  5   def test 2        SortedList  5  2  3   reverse True      5  3  2   def test 3        with pytest raises TypeError           sorted list   SortedList  5  2  3   True      This doesn t work because  reverse  must be passed as a keyword argument  if   name         main         pytest main    file       Thanks to the passing on of  args to super  the list can be initialized and populated with items instead of only being empty   Note that reverse is a keyword-only argument in accordance with PEP 3102

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class BankAccount     def   init   self  balance 0       self balance   int balance     def checkBalance self      Checking opening balance         return self balance    def deposit self  deposit amount 1000      takes in cash deposit amount and updates the balance accordingly      self deposit amount   deposit amount     self balance    deposit amount     return self balance    def withdraw self  withdraw amount 500      takes in cash withdrawal amount and updates the balance accordingly     if self balance  lt  withdraw amount     if amount is greater than balance return   invalid transaction           return  invalid transaction      else        self balance -  withdraw amount       return self balance   class MinimumBalanceAccount BankAccount    subclass MinimumBalanceAccount of the BankAccount class      def   init   self balance 0  minimum balance 500           BankAccount   init   self  balance 0          self minimum balance   minimum balance         self balance   balance - minimum balance          print  Subclass MinimumBalanceAccount of the BankAccount class created        def MinimumBalance self           return self minimum balance  c   BankAccount   print c deposit 50   print c withdraw 10    b   MinimumBalanceAccount 100  50  print b deposit 50   print b withdraw 10   print b MinimumBalance

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class Class1 object       pass  class Class2 Class1       pass   Class2 is a sub-class of Class1

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Subclassing in Python is done as follows   class WindowElement      def print self           pass  class Button WindowElement       def print self           pass   Here is a tutorial about Python that also contains classes and subclasses

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You use   class DerivedClassName BaseClassName     For details  see the Python docs  section 9 5

[python] Python: How do I make a subclass from a superclass?

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