Python中C++类特性的实现原理

<span style="font-size:18px;">#python类的特性</span>

<span style="font-size:18px;">#而且python还可以实现函数的重载，通过不同的参数来做不同的内部实现</span>

<span style="font-size:18px;">#def overload(*args):</span>

<span style="font-size:18px;">#<span style="white-space:pre">	</span>def overload1():</span>

<span style="font-size:18px;">#<span style="white-space:pre">		</span>print("No args")</span>

<span style="font-size:18px;">#<span style="white-space:pre">	</span>def overload2(x):</span>

<span style="font-size:18px;">#<span style="white-space:pre">		</span>print("one args")</span>

<span style="font-size:18px;">#<span style="white-space:pre">	</span>def overload3(x,y):</span>

<span style="font-size:18px;">#<span style="white-space:pre">		</span>print("two args")</span>

<span style="font-size:18px;">#<span style="white-space:pre">	</span>if len(args) == 0:</span>

<span style="font-size:18px;">#<span style="white-space:pre">		</span>overload1()</span>

<span style="font-size:18px;">#<span style="white-space:pre">	</span>elif len(args) == 1:</span>

<span style="font-size:18px;">#<span style="white-space:pre">		</span>overload2(*args)</span>

<span style="font-size:18px;">#<span style="white-space:pre">	</span>else len(args) == 2:</span>

<span style="font-size:18px;">#<span style="white-space:pre">		</span>overload3(*args)</span>

<span style="font-size:18px;">
class Point:
    x = 100
    y = 200
    def __init__(self, *args):
        try:
            self.x = args[0]
            self.y = args[1]
        except ValueError, e:
            print(e.message)
        except IndexError, e:
            print(e.message)

    def trace(self):
        print 'x=%d y=%d' % (self.x, self.y)

    def overload(self):
        print('Point overload')

    def baseMethod(self):
        print('base method!!!!!!')

<strong><span style="color:#ff0000;">    #接口预留，本处没有实现doVirtual，经由子类来实现
    def delegate(self):
        self.doVirtual()</span></strong>

class Point3D(Point):
    z = 0
    def __init__(self, *args):
        try:
            Point.__init__(self, *args)
            self.z = args[2]
        except IndexError, e:
            print e.message

<strong><span style="color:#ff0000;">    #函数重写override
    def trace(self):
        Point.trace(self)
        print 'z=%d' % self.z</span></strong>

 <span style="color:#ff0000;"><strong>   #函数遮挡
    def overload(self, x):
        print('Point3D visible')</strong></span>

class PointProvider(Point):
    def __init__(self, *argc):
        Point.__init__(self, *argc)

    def doVirtual(self):
        print 'Implements doVirtual!'

if __name__ == '__main__':
    p1 = Point(10,20)
    p1.k=100 #变相的给增加了成员
    pk = 'p1.k=%d' % (p1.k)
    print(pk)
    p1.trace()

    p2 = Point(1,1)
    p2.overload()
    #compiler error!!!
    #print(p2.k)

    p = Point3D(1,2,3)
    p.trace()
    #看不见基类的overload了,必须要传入一个参数
    p.overload(100) 

    p2.baseMethod()

    pp = PointProvider(10,20)
    pp.delegate()</span>

所以综上所示：

python可以实现类的继承、重载、重写（多态）、函数覆盖（隐藏基类函数）