我是Python的初学者,请教大师一个问题.
想法是通过类来实现2维坐标(X,Y)列表的处理.代码如下:

import os
import sys

class cls2PtBoundary:
    lngX=0
    lngY=0
    def __init__(self,usrDefault=""):
        self.copy_class(usrSourceData=usrDefault)
            
    def is_same(self,other):
        if isinstance(other,cls2PtBoundary)==False:
            return False
        if self.lngX!=other.lngX:
            return False
        if self.lngY!=other.lngY:
            return False
        return True

    def copy_class(self,usrSourceData=""):
        if isinstance(usrSourceData,cls2PtBoundary)==True:
            self.lngX=usrSourceData.lngX
            self.lngY=usrSourceData.lngY

    def set_value(self,lngX=0,lngY=0):
        self.lngX=lngX
        self.lngY=lngY

    def show(self):
        return "(" + str(self.lngX) + "," + str(self.lngY) + ")"

class cls2PtBoundaryLST:
    lngTotal=0
    usr2PtBoundary=[]
    def __init__(self,lngTotal=0,usrDefault=""):
        self.define(lngTotal=lngTotal,usrDefault=usrDefault)

    def define(self,lngTotal=0,blPreserve=False,usrDefault=""):
        if lngTotal<=0:
            self.lngTotal=0
            self.usr2PtBoundary=[]
        else:
            if blPreserve==True:
                if lngTotal>self.lngTotal:
                    fintIdx=0
                    while fintIdx<(lngTotal-self.lngTotal):
                        self.usr2PtBoundary.append(cls2PtBoundary(usrDefault=usrDefault))
                        fintIdx+=1
                else:
                    self.usr2PtBoundary[lngTotal:]=[]
                self.lngTotal=lngTotal
            else:
                self.lngTotal=lngTotal
                fintIdx=0
                while fintIdx<lngTotal:
                    self.usr2PtBoundary.append(cls2PtBoundary(usrDefault=usrDefault))
                    fintIdx+=1
        return self.lngTotal

    def get_index(self,usrSourceData):
        if self.lngTotal<=0:
            return -1
        flngIndex=0
        while flngIndex<self.lngTotal:
            if self.usr2PtBoundary[flngIndex].is_same(usrSourceData)==True:
                return flngIndex
            flngIndex+=1
        return -1

    def show(self):
        i=0
        fsResult=[]
        while i<self.lngTotal:
            fsResult.append(self.usr2PtBoundary.show())
            i+=1
        return fsResult
   
if __name__=='__main__':
   
    x1=cls2PtBoundary()
    x2=cls2PtBoundary()
    print "x1=" + x1.show()
    print "x2=" + x2.show()

    x1.set_value(1,1)
    x2.set_value(2,2)

    print "x1=" + str(x1.show())
    print "x2=" + str(x2.show())
   
    y1=cls2PtBoundaryLST(2,x1)
    y2=cls2PtBoundaryLST(2,x2)

    print "y1=" + str(y1.show())
    print "y2=" + str(y2.show())

    y2.usr2PtBoundary[1].set_value(3,3)

    print "y1=" + str(y1.show())
    print "y2=" + str(y2.show())
   
   
打印结果出乎我意料:
x1=(0,0)
x2=(0,0)
x1=(1,1)
x2=(2,2)
y1=['(1,1)', '(1,1)']
y2=['(1,1)', '(1,1)']
y1=['(1,1)', '(3,3)']
y2=['(1,1)', '(3,3)']   

为什么Y2列表的值和Y1是一样的呢,改变Y2的值,Y1也会改变,这是为什么.好象Y1和Y2是引用的同一个地址.怎么写代码才能实现Y1和Y2的独立呢
多谢大侠们指点
实在是搞不明白了
Python版本用的是2.6.6
多谢了



[ 本帖最后由 shojnhv 于 2013-9-20 15:22 编辑 ]