4.面对对象

创建一个类：

class MyClass:
    pass
mc = MyClass()
print (mc) # <__main__.MyClass object at 0x7fb803b466a0>

在类中，可以创建变量和函数：

class MyClass:
    name = 'Sam'
    def sayHi(self):
        print ('Hello %s' % self.name)
mc = MyClass()
print (mc.name)
mc.name = 'Lily'
mc.sayHi()

需要注意的是，类中的函数，第一个参数必须为 self。

类中可以继承：

class Vehicle:
    def __init__(self, speed): # 相当于构造函数
        self.speed = speed
    def drive(self, distance):
        print ('need %f hour(s)' % (distance / self.speed))
class Bike(Vehicle): # 集成自 Vehicle
    pass
class Car(Vehicle):
    def __init__(self, speed, fuel):
        Vehicle.__init__(self, speed)
        self.fuel = fuel
    def drive(self, distance):
        Vehicle.drive(self, distance) # 调用超类方法
        print ('need %f fuels' % (distance * self.fuel))
b = Bike(15.0)
c = Car(80.0, 0.012)
b.drive(100.0)
c.drive(100.0)