Inheritance

Re-Implement Rationals

: Rational Class

-   Attributes:

   Numerator

   Denominator

-   Methods:

   print ( ) - should print ‘numerator / denominator’

   add ( other ) - should return a new rational with addition of current and other

   mul ( other ) - should return a new rational with multiplication of current and other

Inheritance

Class Relationships

: Electric-type Pokemon are simply specialized versions of regular Pokemon

Using Inheritance

- We can implement specialized classes using inheritance!

- The class definition allows us to specify that a new class inherits from a superclass:

- We call the more specialized class a subclass of the general class and the general class a superclass of the specialized class.

- The subclass inherits all class attributes of the superclass.

- The subclass can override attributes to specify how it is different from the superclass.

New dot expression rules

How to evaluate:

1. Evaluate < expression >, which yields an object.

2. < name > is matched against the instance attributes of that object; if an attribute with that name exists, its value is returned.

3. If not, the name is looked up in the class, which yields a class attribute value. If it is not found in the class, look in any superclasses.

4. That value is returned unless it is a function, in which case a bound method is returned instead.

Designing for inheritance

- don't repeat yourself; use existing implementations

- attributes that have been overridden are still accessible via class objects

- look up attributes on instances when possible to allow for more specialization

: reuse the general attack instead of rewriting code

: use self.prob over ElectricType.prob