Python笔记-类的单例模式及重载打印

重载如下类：

class Position(object):
    def __init__(self, x = None, y = None):
        self.x = x
        self.y = y
        pass

    def getX(self):
        return self.x

    def getY(self):
        return self.y

    def setX(self, x):
        self.x = x
        pass

    def setY(self, y):
        self.y = y
        pass

    def __repr__(self):

        return '(%d,%d)'%(self.x if self.x else -1, self.y if self.y else -1)
        pass

    pass

Python中的单例：

class CvGraph(object):
    instanceLock = threading.Lock()
    def __init__(self):
        pass

    def __new__(cls, *args, **kwargs):
        if not hasattr(CvGraph, "instance"):
            with CvGraph.instanceLock:
                if not hasattr(CvGraph, "instance"):
                    CvGraph.instance = object.__new__(cls)
                    pass
                pass
            pass
        return CvGraph.instance
        pass
    pass