Python: most idiomatic way to convert None to empty string?

Question

What is the most idiomatic way to do the following?

def xstr(s):
    if s is None:
        return \'\'
    else:
        return s

s = xstr(a) + xstr(b)
         


        

Answer 1

Use short circuit evaluation:

s = a or '' + b or ''

Since + is not a very good operation on strings, better use format strings:

s = "%s%s" % (a or '', b or '')