For loop through the list unless empty?

Question

I've been writing a lot of constructs like this the past couple of days:

things = get_list()
if things:
    for i in things:
        pass # do something with the list
else:
    pass # do something if the list was empty

Lot of junk and I assign the list to a real variable (keeping it in memory longer than needed). Python has simplified a lot of my code up til now... Is there a easy way to do this?

(My understanding is that the else in the for ... else: construct always triggers after it has looped, empty or not - so not what I want)

Answer 1

Use a list comprehension:

def do_something(x):
  return x**2

things = []
result = [do_something(x) for x in things]
print result        # []

things = [1, 2, 3]
result = [do_something(x) for x in things]
print result       # [1, 4, 9]