Unbound error, local variable referenced before assignment

Question

I'm making a small text game for fun. I want to use a function which is located in a function file that I made called functionala.

The function in question, attack() , does not work and the program crashes with the error:

Traceback (most recent call last):
  File "C:\Users\seanm\Desktop\Programming\The mists of Alandria\Mists_of_alandria.py", line 22, in <module>
    functionala2.attack()
  File "C:\Users\seanm\Desktop\Programming\The mists of Alandria\functionala2.py", line 27, in attack
    variablestamina += 2
UnboundLocalError: local variable 'variablestamina' referenced before assignment

The new and improved version of the functionala file is what seems to be causing the problem:

variablestamina = 20
variablehealth = 40
variablemonsterhealth = 30
variableattacktype1 = ("Lightattack")
variableattacktype2 = ("Mediumattack")
variableattacktype3 = ("Heavyattack")

def attack():
     variableattackquery = input("You can execute three types of attacks. Lightattack does 2 damage and takes no stamina. Mediumattack does 4 damage and takes 2 stamina. Heavyattack does 7 damage and takes 5 stamina. You can only do one per turn: ")
     if variableattackquery == variableattacktype1:
        variablemonsterhealth -= 2
        variablestamina -= 2
     if variableattackquery == variableattacktype2:
        variablemonsterhealth -= 4
        variablestamina -= 4
     if variableattackquery == variableattacktype3:
        variablemonsterhealth -= 7
        variablestamina -= 7 
     variablestamina += 2
     variablestamina = min(20, variablestamina)
     print ("The "+monster+" has "+str(variablemonsterhealth)+" health left")
     print ("You have "+str(variablestamina)+" stamina left")
     monsterattack = random.randrange(4,6)
     variablehealth -= monsterattack
     print ("The "+monster+" attacks you for "+str(monsterattack))
     print ("You have "+str(variablehealth)+" health left")
     print()

Answer 1

This seems a cleaner way of doing it, all in a single file. you may want to look at using classes.

From console, call game() to start the game, that's it. The game will end when either monster or you have health <= 0.

Code:

from random import randrange

def game():
    stamina = 20
    health = 40
    monsterhealth = 30
    monster = 'orc'
    attacks = {'light':(-2,0),'medium':(-4,-2),'heavy':(-7,-4)}
    while True:
        a = input('you can execute 3 types of attacks, light, medium or heavy... pick one.')
        a = a.lower().strip()
        if a in attacks:
            stamina, health, monsterhealth = attack(stamina, health, monsterhealth, monster, attacks[a])
            if stamina <= 0:
                print 'you have died...'
                break
            elif monsterhealth <= 0:
                print 'the {} has died...'.format(monster)
                break
        else:
            break

def attack(stamina, health, monsterhealth, monster, att):
    monsterhealth += att[0]
    stamina += att[1]
    stamina = min(20, stamina)
    print('the {} has {} health remaining'.format(monster,monsterhealth))
    print('you have {} stamina remaining'.format(stamina))
    ma = randrange(4,6)
    health -= ma
    print('the {} attacks you for {}'.format(monster,ma))
    print('you have {} health left'.format(health))
    return stamina, health, monsterhealth

NB: Even doing this in a single file, you need to scope the variables to the "main" procedure ( game ), and pass them to the attack function. Otherwise, referring to these names will raise the same error, and you can reproduce this like so:

m = 1
def foo():
   m += 1  '## m doesn't exist within scope of foo, so it will raise the same error

HOWEVER, and this may be confusing, the following will not raise an error:

m = 1
def foo():
   print m

Nor will this:

m = 1
def foo():
   a = m
   print a

But both of those seem kind of hack-y and it's usually better to pass values from the main procedure to called functions/methods/etc and return appropriate values to the caller.