// 8 day(2016/8/11)

38. In python , it is oop.

     class Baskball:

         def setName(self, name):

                self.name = name

         def kick(self):

                print('my name is %s' % self.name)

      baskball = Baskball()

      baskball.setName('baskball')

      baskball.kick()

     -> my name is baskball

     class Ball:

         def __init__(self, name):

              self.name = name

         def kick(self):

              print('my name is %s' % self.name)

       b = Ball('tom')

       b.kick()

       -> my name is tom

 

39. In python ,how to define private variable,

     such as:

     class Person:

          name = 'roy'

     p = Person()

     print(p.name)

     -> roy

     if you use:

    class Person:

          __name = 'roy'

     p = Person()

     print(p.__name) || print(p.name)

     -> error

     if you use __ before variable ,you can access it direct.

     class Person:

           __name = 'roy'

           def getName(self):

                return self.__name

     p = Person()

     print(p.getName())

     -> roy   

    class Person:

       __name = 'roy'

    p  = Person()

    print(p._Person__name)

    -> roy

 

40. inheritance mechanism

      class SubClassName:(ParentClassName):

                ……

     class Parent:

          def hello(self):

                print('write code change world')

     class Child(Parent):

          pass

     p = Parent()

     p.hello()

     c = Child()

     c.hello()

     ->

     write code change world

     write code change world

     if subclass methon is same with parent , it will cover parent method, such as:

     class Child(Parent):

          def hello(self):

              print('believe youself')

     c = Child()

     c.hello()

     -> believe youself

     now we will study a simple example:

     import random as r

     class Fish:

          def __init__(self):

              self.x = r.randint(0,10)

              self.y = r.randint(0,10)

          def move(self):

             self.x -= 1

             print('my position is:',self.x, self.y)

     class Shark(Fish):

         def __init__(self):

            #Fish.__init__(self)

            super().__init__()

            self.hungry = True

        def eat(self):

             if self.hungry:

                print('eat eat eat')

                self.hungry = False

            else:

                print('not hungry')

       1,Fish.__init__(self)

       2,super().__init__() 

       1 and 2 is same ,if you not add this ,you invoke move in Shark ,it will error, because ,__init__ will cover parent method, you call move() ,it will not found x and y. if you use  1 and 2, it will solve this question

      multiply parent class:

      class subClassName:(parent1ClassName, parent2ClassName):

           ……

    

     class Base1:

         def fool1(self):

               print('it is fool1')

     class Base2:

        def fool2(self):

              print('it is fool2')

     class c(Base1, Base2):

           pass

     c = c()

     c.fool1()

     c.fool2()

     -> it is fool1

     -> it is fool2