python - Set instance variable as default parameter to class function -

i have class function takes 4 arguments, class member variables in practice. 1 of these arguments modified @ time , rest of time would-be defaults (current values of class member variables) passed function/written out though aren't changing.

i thought best make these class member variables defaults, i'm having hard time getting best syntax. following code produces behavior desire - using class member variable default parameter function. it's ugly:

class test:     def __init__(self, a, b):         self.a =         self.b = b      def testfunc(self, param = none):         if not param:             param = self.a         print(param)   if __name__ == '__main__':     a1 = test(1, 3)     a1.testfunc()     a2 = test(5, 5)     a2.testfunc()    #(prints 1 , 5 when called) 

i use following:

    def testfunc(self, param = self.a):         print(param) 

but gives error:

nameerror: name 'self' not defined 

what's better way this?

your first attempt pythonic, thing change test:

 def testfunc(self, param = none):         if param none:             param = self.a         print(param) 

the problem testing false 0 , empty container (including empty string) resolve false.

if have large number of these, see understanding kwargs in python