Check if condition matches multiple variables

Question

I have a method/function that get's passed several variables that possibly have None value. How can I check all variables for None value and replace it with a string in the most pythonic way possible?

Example code:

def logData(self, var1=None, var2=None, var3=None):
    if var1 is None:
         var1 = "---"
    if var2 is None:
         var2 = "---"
    if var3 is None:
         var3 = "---"

    # what I would prefer / pseudo code:
    if list(var1, var2, var3) is None:
         list[1] = "---"

Answer 1

var1, var2, var3 = (a or '---' for a in [var1, var2, var3])

Answer 2

Use tuple unpacking:

var1, var2, var3 = ['---' if (x is None) else x for x in (var1, var2, var3)]

Answer 3

You could achieve this by using **kwargs:

def logData(self, **kwargs):
  for key,value in kwargs.iteritems():
    if value is None:
      # do assignment ...