[EMAIL PROTECTED] napisał(a): > Hi, I have just encountered a Python behaviour I wouldn't expect. Take > the following code: > > ------------------------------------------------------------------------ > class Parent: > a = 1 > > def m (self, param = a): > print "param = %d" % param > > class Child (Parent): > a = 2 > > > p = Parent () > p.m () > > c = Child () > c.m () > ------------------------------------------------------------------------ > > I would expect to receive the following output: > param = 1 > param = 2 > > But actually I get: > param = 1 > param = 1 > > Is this the correct behaviour, and then why, or is it a bug? For > reference, I am using Python 2.5.1 on UNIX. > > Thanks in advance!
I expect it's because default values for parameters are evaluated and bound at definition time. So once "def m (self, param = a):" line executes, the default value for parameter is forever bound to be 1. What you can do is for example: > def m (self, param = None): > if param is None: param = self.a > print "param = %d" % param Regards, Marek -- http://mail.python.org/mailman/listinfo/python-list
