如何跟踪Python中的分数增量？

Question

I am writing a simple game program in Python where a user is prompted to select from "healthy" and "unhealthy" items in a grocery store. Each time the user selects a healthy item their "Health Score (initially 100) goes up. Each time they select from the unhealthy items their score goes down.

My code adds and subtracts from the initial Health Score of 100, but doesn't keep track of the most updated score after each selection. I want to give the user their new total after each transaction (new_hscore) and their grand total at the end (final_score), but I'm not sure how to do that.

Is it done with lists? Do I use .append? Any help would be greatly appreciated! Thanks in advance!

Here is my code: http://pastebin.com/TvyURsMb

You can see right away what I'm trying to do when you scroll down to the "def inner():" function.

EDIT: I got it working! Thank you all who contributed. I learned a lot. My final 'score-keeping' working code is here: http://pastebin.com/BVVJAnKa

Answer 1

You can do something simple like this:

hp_history = [10]

def initial_health():
    return hp_history[0]

def cur_health():
    return hp_history[-1]

def affect_health(delta):
    hp_history.append(cur_health() + delta)
    return cur_health()

Demonstration:

>>> cur_health()
10
>>> affect_health(20)
30
>>> affect_health(-5)
25
>>> affect_health(17)
42
>>> cur_health()
42
>>> print hp_history
[10, 30, 25, 42]

Answer 2

You can't store module level variables like that. Any attempt to write to that variable will create a local variable. Examine the behavior of this script:

s = 0
def f():
    s = 10
    print s

f()
print s

Output:

10
0

Instead you should be moving towards an object-oriented approach. Start placing your code in a class:

class HeathlyGame():

    def __init__(self):
        self.init_hscore = 100
        self.final_score = 0

    # Beginning. Proceed or quit game.
    def start(self):
            print "Your shopping habits will either help you live longer or they will help you die sooner. No kidding! Wanna find out which one of the two in your case?", yn

            find_out = raw_input(select).upper()

...

game = HeathlyGame()
game.start()

This will allow you to create multiple versions of the game in memory at once, and each can store their own copy of the score.

For more on classes, try this link: http://en.wikibooks.org/wiki/A_Beginner%27s_Python_Tutorial/Classes

Answer 3

The problem seems to be you are always starting at init_hp , forgetting your cur_hp doing

init_hp = 10
while True:
    food = choose_food()
    if "cereal" in food:
        cur_hp = init_hp - 5

# ..

But you need:

init_hp = 10
cur_hp = init_hp

while True:
    food = choose_food()
    if "cereal" in food:
        cur_hp -= 5

# ..

Answer 4

You can use a generator!

A generator is basically a function that keeps track of the state of its objects even after you leave the function and call it again. Instead of using 'return' and the end, you use 'yield'. Try something like this:

def HealthScore(add):
    score = 100
    while 1:
        score += add
        yield score

if you call HealthScore(-5), it will return 95. If you then call HealthScore(5), it will return 100.