assigning class variable as default value to class method argument

Question

I would like to build a method inside a class with default values arguments taken from this class. In general I do filtering on some data. Inside my class I have a method wh

Answer 1

Default arguments get evaluated only once, when the definition is executed. Instead, do this:

def doSomething(self, a=None):
    if a is None:
        a = self.z
    self.z = 3
    self.b = a

See also http://docs.python.org/release/3.3.0/tutorial/controlflow.html#more-on-defining-functions.