注意python dict的内容变化

下面的代码，执行有错：

class TripleDataFilter():
    def __init__(self):
        self.idFilter = None
        self.propFilter = None
        self.valueFilter = None
        self.prefilter = None
        self.filterOrder = []
        self.filterMap = {"id":self.idFilter, 
                        "prop_name":self.propFilter,
                        "prop_value":self.valueFilter}
         
    def read_conf(self, confFile):
        if (not os.path.isfile(confFile)) or "" == confFile:
            sys.stderr.write(confFile + " is not exit!\n")
            return False

        config = ConfigParser.ConfigParser()
        config.read(confFile)
        if "WORK_DIR" in config.sections():
            workDir = config.items("WORK_DIR")[0][1].strip()
        else:   
            workDir = "."
        prefilterConf = config.items("PREFILTER")[0][1]
        if "none" != prefilterConf.lower():
            self.preFilter = prefilter.PreFilter()
            self.preFilter.read_conf(prefilterConf)
         
        fItemList = config.items("FILTER_CONF_FILES")
        for fItem in fItemList:
            segName = fItem[0].strip()
            filePath = fItem[1].strip()
            if os.path.split(filePath)[0] == "":
                filePath = workDir + "/" + filePath
            if "id_conf" == segName:
                self.idFilter = SegmentFilter("id");
                self.idFilter.read_conf(filePath, self.preFilter)
            elif "prop_conf" ==segName:
                self.propFilter = SegmentFilter("prop");
                self.propFilter.read_conf(filePath, self.preFilter)
            elif "value_conf" == segName:
                print "conf value"
                self.valueFilter = SegmentFilter("value");
                self.valueFilter.read_conf(filePath, self.preFilter)
            else:   
                sys.stderr.write("字段名错误 %s\n" % segName)
                return False       
                        
        self.filterOrder = config.items("FILTER_ORDER")
        self.filterOrder.sort(key = lambda x:x[1]) 
                
   
    def filter(self, tripleExt):
        for filterType in self.filterOrder:
            if self.filterMap[filterType[0]]:
                self.filterMap[filterType[0]].filter(tripleExt)
            else:   
                print filterType[0] + " is null"

执行filter时，会说filterMap里的元素都为None。

原因是，创建dict 时，会重新复制一份新的对象到dict中。

最开始，所有的filter都为None，存入了dict中。

后来，虽然filter都被赋值，但dict中的值没有改变，仍为None。