Question

So, Python functions can return multiple values. It struck me that it would be convenient (though a bit less readable) if the following were possible.

a = [[1,2],[3,4]]  def cord():     return 1, 1  def printa(y,x):     print a[y][x]  printa(cord()) 

…but it’s not. I’m aware that you can do the same thing by dumping both return values into temporary variables, but it doesn’t seem as elegant. I could also rewrite the last line as ‘printa(cord()[0], cord()[1])’, but that would execute cord() twice.

Is there an elegant, efficient way to do this? Or should I just see that quote about premature optimization and forget about this?

Answer 1

printa(*cord()) 

The * here is an argument expansion operator… well I forget what it’s technically called, but in this context it takes a list or tuple and expands it out so the function sees each list/tuple element as a separate argument.

It’s basically the reverse of the * you might use to capture all non-keyword arguments in a function definition:

def fn(*args):     # args is now a tuple of the non-keyworded arguments     print args  fn(1, 2, 3, 4, 5) 

prints (1, 2, 3, 4, 5)

fn(*[1, 2, 3, 4, 5]) 

does the same.