Beginner question: returning a boolean value from a function in Python

Question

I'm trying to get this rock paper scissors game to either return a Boolean value, as in set player_wins to True or False, depending on if the player wins, or to refactor this code entirely so that it doesn't use a while loop. I'm coming from the sysadmin side of the world, so please be gentle if this is written in the wrong style. I have tried a few things, and I understand TIMTOWTDI, and would just like some input.

Thanks.

import random

global player_wins
player_wins=None

def rps():

    player_score = 0
    cpu_score = 0

    while player_score < 3 and cpu_score < 3:

        WEAPONS = 'Rock', 'Paper', 'Scissors'

        for i in range(0, 3):
          print "%d %s" % (i + 1, WEAPONS[i])

        player = int(input ("Choose from 1-3: ")) - 1
        cpu = random.choice(range(0, 3))

        print "%s vs %s" % (WEAPONS[player], WEAPONS[cpu])
        if cpu != player:
          if (player - cpu) % 3 < (cpu - player) % 3:
            player_score += 1
            print "Player wins %d games\n" % player_score
          else:
            cpu_score += 1
            print "CPU wins %d games\n" % cpu_score
        else:
          print "tie!\n"
rps()

I'm trying to do something like this:

   print "%s vs %s" % (WEAPONS[player], WEAPONS[cpu])
    if cpu != player:
      if (player - cpu) % 3 < (cpu - player) % 3:
        player_score += 1
        print "Player wins %d games\n" % player_score
        if player_score == 3:
            return player_wins==True
      else:
        cpu_score += 1
        print "CPU wins %d games\n" % cpu_score
        if cpu_score == 3:
            return player_wins==False
    else:
      print "tie!\n"

Solution 1

Ignoring the refactoring issues, you need to understand functions and return values. You don't need a global at all. Ever. You can do this:

def rps():
    # Code to determine if player wins
    if player_wins:
        return True

    return False

Then, just assign a value to the variable outside this function like so:

player_wins = rps()

It will be assigned the return value (either True or False) of the function you just called.

---

After the comments, I decided to add that idiomatically, this would be better expressed thus:

 def rps(): 
     # Code to determine if player wins, assigning a boolean value (True or False)
     # to the variable player_wins.

     return player_wins

 pw = rps()

This assigns the boolean value of player_wins (inside the function) to the pw variable outside the function.

Solution 2

Have your tried using the 'return' keyword?

def rps():
    return True