From 9b6d84309c8b554ab87b19e27eadbe550d5204a6 Mon Sep 17 00:00:00 2001 From: Keith Miyake Date: Thu, 19 Oct 2017 22:26:32 -0700 Subject: [python3/en] Add single inheritance section --- python3.html.markdown | 128 +++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 111 insertions(+), 17 deletions(-) diff --git a/python3.html.markdown b/python3.html.markdown index 5aa61b65..e02aed43 100644 --- a/python3.html.markdown +++ b/python3.html.markdown @@ -669,7 +669,7 @@ class Human: # An instance method. All methods take "self" as the first argument def say(self, msg): - print ("{name}: {message}".format(name=self.name, message=msg)) + print("{name}: {message}".format(name=self.name, message=msg)) # Another instance method def sing(self): @@ -740,7 +740,101 @@ if __name__ == '__main__': #################################################### -## 6.1 Multiple Inheritance +## 6.1 Inheritance +#################################################### + +# Inheritance allows new child classes to be defined that inherit methods and +# variables from their parent class. + +# Using the Human class defined above as the base or parent class, we can +# define a child class, Superhero, which inherits the class variables like +# "species", "name", and "age", as well as methods, like "sing" and "grunt" +# from the Human class, but can also have its own unique properties. + +# To take advantage of modularization by file you could place the classes above in their own files, +# say, human.py + +# To import functions from other files use the following format +# from "filename-without-extension" import "function-or-class" + +from human import Human + + +# Specify the parent class(es) as parameters to the class definition +class Superhero(Human): + + # If the child class should inherit all of the parent's definitions without + # any modifications, you can just use the "pass" keyword (and nothing else) + # but in this case it is commented out to allow for a unique child class: + # pass + + # Child classes can override their parents' attributes + species = 'Superhuman' + + # Children automatically inherit their parent class's constructor including + # its arguments, but can also define additional arguments or definitions + # and override its methods such as the class constructor. + # This constructor inherits the "name" argument from the "Human" class and + # adds the "superpower" and "movie" arguments: + def __init__(self, name, movie=False, + superpowers=["super strength", "bulletproofing"]): + + # add additional class attributes: + self.fictional = True + self.movie = movie + self.superpowers = superpowers + + # The "super" function lets you access the parent class's methods + # that are overwritten by the child, in this case, the __init__ method. + # This calls the parent class constructor: + super().__init__(name) + + # overload the sing method + def sing(self): + return 'Dun, dun, DUN!' + + # add an additional class method + def boast(self): + for power in self.superpowers: + print("I wield the power of {pow}!".format(pow=power)) + + +if __name__ == '__main__': + sup = Superhero(name="Tick") + + # Instance type checks + if isinstance(sup, Human): + print('I am human') + if type(sup) is Superhero: + print('I am a superhero') + + # Get the Method Resolution search Order used by both getattr() and super() + # This attribute is dynamic and can be updated + print(Superhero.__mro__) # => (, + # => , ) + + # Calls parent method but uses its own class attribute + print(sup.get_species()) # => Superhero + + # Calls overloaded method + print(sup.sing()) # => Dun, dun, DUN! + + # Calls method from Human + sup.say('Spoon') # => Tick: Spoon + + # Call method that exists only in Superhero + sup.boast() # => I wield the power of super strength! + # => I wield the power of bulletproofing! + + # Inherited class attribute + sup.age = 31 + print(sup.age) # => 31 + + # Attribute that only exists within Superhero + print('Am I Oscar eligible? ' + str(sup.movie)) + +#################################################### +## 6.2 Multiple Inheritance #################################################### # Another class definition @@ -766,20 +860,16 @@ if __name__ == '__main__': print(b.fly) # To take advantage of modularization by file you could place the classes above in their own files, -# say, human.py and bat.py +# say, superhero.py and bat.py # To import functions from other files use the following format # from "filename-without-extension" import "function-or-class" - # superhero.py -from human import Human +from superhero import Superhero from bat import Bat -# Batman inherits from both Human and Bat -class Batman(Human, Bat): - - # Batman has its own value for the species class attribute - species = 'Superhero' +# Batman inherits from both Superhero and Bat +class Batman(Superhero, Bat): def __init__(self, *args, **kwargs): # Typically to inherit attributes you have to call super: @@ -789,7 +879,8 @@ class Batman(Human, Bat): # So instead we explicitly call __init__ for all ancestors. # The use of *args and **kwargs allows for a clean way to pass arguments, # with each parent "peeling a layer of the onion". - Human.__init__(self, 'anonymous', *args, **kwargs) + Superhero.__init__(self, 'anonymous', movie=True, + superpowers=['Wealthy'], *args, **kwargs) Bat.__init__(self, *args, can_fly=False, **kwargs) # override the value for the name attribute self.name = 'Sad Affleck' @@ -802,8 +893,8 @@ if __name__ == '__main__': sup = Batman() # Instance type checks - if isinstance(sup, Human): - print('I am human') + if isinstance(sup, Superhero): + print('I am a superhero) if isinstance(sup, Bat): print('I am bat') if type(sup) is Batman: @@ -811,10 +902,13 @@ if __name__ == '__main__': # Get the Method Resolution search Order used by both getattr() and super(). # This attribute is dynamic and can be updated - print(Batman.__mro__) # => (, , , ) + print(Batman.__mro__) # => (, + # => , + # => , + # => , ) # Calls parent method but uses its own class attribute - print(sup.get_species()) # => Superhero + print(sup.get_species()) # => Superhuman # Calls overloaded method print(sup.sing()) # => nan nan nan nan nan batman! @@ -827,10 +921,10 @@ if __name__ == '__main__': # Inherited class attribute sup.age = 100 - print(sup.age) + print(sup.age) # => 100 # Inherited attribute from 2nd ancestor whose default value was overridden. - print('Can I fly? ' + str(sup.fly)) + print('Can I fly? ' + str(sup.fly)) # => Can I fly? False -- cgit v1.2.3 From 55efb934b8d7f2034020d17e331f02b852952012 Mon Sep 17 00:00:00 2001 From: Keith Miyake Date: Mon, 23 Oct 2017 15:11:13 -0700 Subject: python3/en cleanup for single inheritance merge --- python3.html.markdown | 20 +++++--------------- 1 file changed, 5 insertions(+), 15 deletions(-) diff --git a/python3.html.markdown b/python3.html.markdown index e02aed43..37987582 100644 --- a/python3.html.markdown +++ b/python3.html.markdown @@ -785,7 +785,7 @@ class Superhero(Human): self.superpowers = superpowers # The "super" function lets you access the parent class's methods - # that are overwritten by the child, in this case, the __init__ method. + # that are overridden by the child, in this case, the __init__ method. # This calls the parent class constructor: super().__init__(name) @@ -814,7 +814,7 @@ if __name__ == '__main__': # => , ) # Calls parent method but uses its own class attribute - print(sup.get_species()) # => Superhero + print(sup.get_species()) # => Superhuman # Calls overloaded method print(sup.sing()) # => Dun, dun, DUN! @@ -838,6 +838,7 @@ if __name__ == '__main__': #################################################### # Another class definition +# bat.py class Bat: species = 'Baty' @@ -859,16 +860,13 @@ if __name__ == '__main__': print(b.say('hello')) print(b.fly) -# To take advantage of modularization by file you could place the classes above in their own files, -# say, superhero.py and bat.py -# To import functions from other files use the following format -# from "filename-without-extension" import "function-or-class" +# And yet another class definition that inherits from Superhero and Bat # superhero.py from superhero import Superhero from bat import Bat -# Batman inherits from both Superhero and Bat +# Define Batman as a child that inherits from both Superhero and Bat class Batman(Superhero, Bat): def __init__(self, *args, **kwargs): @@ -892,14 +890,6 @@ class Batman(Superhero, Bat): if __name__ == '__main__': sup = Batman() - # Instance type checks - if isinstance(sup, Superhero): - print('I am a superhero) - if isinstance(sup, Bat): - print('I am bat') - if type(sup) is Batman: - print('I am Batman') - # Get the Method Resolution search Order used by both getattr() and super(). # This attribute is dynamic and can be updated print(Batman.__mro__) # => (, -- cgit v1.2.3