Python Base Five

// 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