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== 13.2#h(0.6em)Attribute access


  
    
=== Learning objectives


    By the end of this section you should be able to


    - Implement a subclass that accesses inherited attributes from the superclass.
- Write a subclass's \_\_init\_\_() that inherits superclass instance attributes and creates new instance attributes.


  
  
    
=== Creating a simple subclass


    Subclasses have access to the attributes inherited from the superclass. When the subclass's \_\_init\_\_() isn't explicitly defined, the superclass's \_\_init\_\_() method is called. Accessing both types of attributes uses the same syntax.


    #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[
#emph[Defining a simple subclass]


      #link("https://www.openstax.org/r/simple-subclass")[Defining a simple subclass; ch 13, video 3]
]


    #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[
#emph[Using simple subclasses]
]


  
  
    
=== Using \_\_init\_\_() to create and inherit instance attributes


    A programmer often wants a subclass to have new instance attributes as well as those inherited from the superclass. Explicitly defining a subclass's \_\_init\_\_() involves defining instance attributes and assigning instance attributes inherited from the superclass.


    #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[
#emph[Defining \_\_init\_\_() in a subclass]


      #link("https://www.openstax.org/r/init-in-a-subclass")[Defining \_init\_() in a subclass; ch 13, video 4]
]


    #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[
#emph[Accessing a subclass's attributes]


      Consider the Employee and Developer example code:


      
    class Employee:
      count = 0
      def \_\_init\_\_(self):
        Employee.count += 1
        self.e\_id = Employee.count
        self.hire\_year = 2023

      def emp\_display(self):
        print(f"Employee {self.e\_id} hired in {self.hire\_year}")

    class Developer(Employee):
      def \_\_init\_\_(self):
        Employee.count += 1
        self.e\_id = Employee.count
        self.hire\_year = 2023
        self.lang\_xp = \["Python", "C++", "Java"\]

      def dev\_display(self):
        print(f"Proficient in {self.lang\_xp}")
    
    emp\_1 = Employee()
    dev\_1 = Developer()
]


  
  #notebox("Note", rgb("#8a94a6"), rgb("#556666"), rgb("#f7f8fa"))[
#emph[Creating a subclass with an instance attribute]


    Given a class Dessert, create a class, Cupcake, inherited from Dessert. Cupcake class methods:


    - \_\_init\_\_(self): initializes inherited instance attribute ingredients with \["butter", "sugar", "eggs", "flour"\], and initializes instance attribute frosting with "buttercream"
- display(self): prints a cupcake's ingredients and frosting


    Then call the display() method on a new Cupcake object. The output should match:


    
    Made with \["butter", "sugar", "eggs", "flour"\] and topped with buttercream frosting
    class Dessert:
    def \_\_init\_\_(self):
        self.ingredients = \["butter", "sugar", "eggs", "flour"\]

\# Define Child class

bday\_cake = Cupcake()
bday\_cake.display()
]