[Tutor] Use of 'or'

[Tim Golden]

Stephen Nelson-Smith wrote:
> A friend of mine mentioned what he called the 'pythonic' idiom of:
> 
> print a or b
> 
> Isn't this a 'clever' kind or ternary - an if / else kind of thing?

I would say it's perfectly idiomatic in Python, but
not as a ternary. If you want a ternary use the
(relatively) recently-introduced:

a if <cond> else b

eg:

things = [1, 2 ,3]
print "%d thing%s found" % (len (things), "" if len (things) == 1 else "s")

Before this operator came along, people used to use
more-or-less clever-clever tricks with boolean operators
or using the fact that bool / int are interchangeable:

['s', ''][len (things) == 1]

The "a or b" idiom is most commonly used for default-type
situations:

def f (a, b=None):
  print "a", b or "<Unknown>"


> I don't warm to it... should I?

Up to you :) But I regard it as a useful idiom.

TJG