Python class instance vs. class variables -

i trying define list instance variable within class acting class variable.

class thing:     def __init__(self, name, stuff):         self.name = name         self.dict = []         item in stuff:             self.dict.append(item)      def getname(self):         return self.name      def getlist(self):         return self.dict      def inc_datecnt(self,date):         item in self.dict:             if item.has_key(date):                  item[date] += 1    list = [] dates=['july1,2015', 'july2,2015', 'july3,2015'] datecnts = [] date in dates:     datecnts.append({date : 0})  list.append(thing('a', datecnts)) list.append(thing('b', datecnts))   item in list:     print "\n", item.getname()     item.inc_datecnt('july1,2015')     subitem in item.getlist():         print subitem 

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when execute get:

a {'july1,2015': 1} {'july2,2015': 0} {'july3,2015': 0}  b {'july1,2015': 2} {'july2,2015': 0} {'july3,2015': 0} 

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i seem increment single class dictionary element july1,2015 when want (and expect) incrementing instance variable.

help

when passing datecnts list thing object's constructor, passing reference (and list mutable , dict mutable) , hence if make changes dict a thing object, reflect in b , since b has same reference. should try copy.deepcopy of datecnts , send a , b separately.

example -

import copy list.append(thing('a', copy.deepcopy(datecnts))) list.append(thing('b', copy.deepcopy(datecnts)))