How to detect that a function argument is the default one

[ast]

Hello

Here is what I would like to implement

class Circle:

   def __init__(center=(0,0), radius=10, mass=1)):
       self.center = center
       self.radius = radius

       if  "mass is the default one":       <-----
           self.mass = radius**2
       else:
           self.mass = mass

I cant just test if mass == 1: because if I call
C1 = Circle((0,0), 7, 1)
then in that case I want: self.mass = 1

If i call  C2 = Circle((6,8), 8) 
then in that case I want: self.mass = radius**2

I have the idea to write:

def __init__(center=(0,0), radius=10, mass=None)):

   if  mass == None: 
       self.mass = radius**2
   else:
       self.mass = mass

but maybe Python provides something clever.

Thx


--
https://mail.python.org/mailman/listinfo/python-list