如何定义全局名称？

Question

I'm trying to learn Python, but I'm having some trouble making a sort of text adventure game because of global names, here's my code.

def startcave():
    print "You awake in an dark cave. You can't remember your past, but you need to find a way out. You feel hungry, although tired."
    print "Would you like to delve deeper via a cave passage, or look for a way out in this room?"
    answer = raw_input("Do you go -Deeper-, -Search-, or -Rest-?").lower()
    if answer == "Deeper" or answer == "deeper":
        lowcave1()
    elif answer == "Search" or answer == "search":
        searchcave()
    elif answer == "Rest" or answer == "rest":
        caverest()
    else:
        print "You must either say -Deeper- or -Search-"
        startcave()

startcave()

def lowcave1():
    print "You go deeper into the cave, walking down a steadily reclining corridor for some time, you have lost track of time."
    print "There is a large ledge before you. You can jump down, but there is no way back up."
    print "The cave may be dangerous, and you could end up being trapped. Do you turn back?"
    answer = raw_input("Do you -Jump- or -Turn back-?").lower()
    if answer == "Jump" or answer == "jump":
        lowcave2()
    elif answer == "Turn back":
        caverest2()

lowcave1()

If I answer "Deeper", this error occurs.

Traceback (most recent call last):
  File "C:\Users\Student\Desktop\Cavestuff.py", line 15, in <module>
    startcave()
  File "C:\Users\Student\Desktop\Cavestuff.py", line 6, in startcave
    lowcave1()
NameError: global name 'lowcave1' is not defined

Answer 1

Use the global keyword to indicate you mean to use a global variable.

foo = 123

def bar():
    global foo
    print(foo)

Answer 2

You need to define all functions before calling them

def startcave():
    print "You awake in an dark cave. You can't remember your past, but you need to find a way out. You feel hungry, although tired."
    print "Would you like to delve deeper via a cave passage, or look for a way out in this room?"
    answer = raw_input("Do you go -Deeper-, -Search-, or -Rest-?").lower()
    if answer == "Deeper" or answer == "deeper":
        lowcave1()
    elif answer == "Search" or answer == "search":
        searchcave()
    elif answer == "Rest" or answer == "rest":
        caverest()
    else:
        print "You must either say -Deeper- or -Search-"
        startcave()

def lowcave1():
    print "You go deeper into the cave, walking down a steadily reclining corridor for some time, you have lost track of time."
    print "There is a large ledge before you. You can jump down, but there is no way back up."
    print "The cave may be dangerous, and you could end up being trapped. Do you turn back?"
    answer = raw_input("Do you -Jump- or -Turn back-?").lower()
    if answer == "Jump" or answer == "jump":
        lowcave2()
    elif answer == "Turn back":
        caverest2()

startcave()

lowcave1()

Answer 3

Ok, you should use global .

a = 1
print '1: ', a # Prints 1: 1

def f1():
  a = 2
  print '2: ', a

f1() # Prints 2: 2

print '3: ', a # Prints 3: 1

def f2():
  global a
  a = 3
  print '4: ', a

f2() # Prints 4: 3

print '5: ', a # Prints 5: 3