> Andrew Jaffe wrote: > >> Hi, >> >> I have a class with various class-level variables which are used to >> store global state information for all instances of a class. These are >> set by a classmethod as in the following >> >> class sup(object): >> cvar1 = None >> cvar2 = None >> >> @classmethod >> def setcvar1(cls, val): >> cls.cvar1 = val >> >> @classmethod >> def setcvar2(cls, val): >> cls.cvar2 = val >> >> @classmethod >> def printcvars(cls): >> print cls.cvar1, cls.cvar2 >> >> Now, the problem comes when I want to subclass this class. If I >> override the setcvar1 method to do some new things special to this >> class, and then call the sup.setcvar1() method, it all works fine: >> >> class sub(sup): >> cvar1a = None >> >> @classmethod >> def setcvar1(cls, val, vala): >> cls.cvar1a = vala >> sup.setcvar1(val) >> >> @classmethod >> def printcvars(cls): >> print cls.cvar1a >> sup.printcvars() >> >> This works fine, and sets cvar and cvar2 for both classes. >> >> However, if I *don't* override the setcvar2 method, but I call >> sub.setcvar2(val) directly, then only sub.cvar2 gets set; it is no >> longer identical to sup.cvar1! >> >> In particular, >> sub.setcvar1(1,10) >> sub.setcvar2(2) >> sub.printcvars() >> prints >> 10 >> 1 None >> >> i.e. sub.cvar1, sub.cvar1a, sub.cvar2= 1 10 2 >> but sup.cvar1, cvar2= 1 None >> >> This behavior is "expected", but is it desirable? >> > > You are experiencing this problem because you are using hard-wired class > names. Try using (for example) self.__class__. That way, even if your > method is inheroted by a subclass it will use the class of the object it > finds itself a method of. No need to use classmethods.
The problem is that I actually do want to call these methods on the class itself, before I've made any instances. A -- http://mail.python.org/mailman/listinfo/python-list
