蟒蛇：分配錯誤

Question

我完成一個基於文本的遊戲的介紹到蟒蛇上課前局部變量引用。它沒有完成，但是當我遇到這個錯誤信息時，我正在處理main_menu函數和main_menu函數中調用的函數。我也遇到過這種錯誤多次在我的學習經驗和分配變量時，它通常被認爲是一個基本的錯誤，但是這其中有我難倒... 這是有問題的腳本（在回溯線BOLD評論） ：

import random 
from sys import exit 


# Item variables 
coal = ('Coal', 'some coal which can be used in a furnace.') 
eng_key = ('Key', 'a key to a house.') 
bomb = ('Bomb', 'a combustible device which creates a powerfull explosion. Possibly used for demolition...') 
tonic = ('Tonic', 'a weak healing tonic. Adds \'5\' health points.') 
sTonic = ('Super Tonic', 'a strong healing tonic. Adds \'10\' health points.') 


# LOCATIONS 
# Below are the possible locations you can 'travel' to, along with a title (first item in tuple), a description, any items that might be found in the location which can be discovered and entered into 'inventory' through 'search' command 
# location variable = (title, description, item for discovery) 
sub_base = ('Sub-Base', 'This is DeepBlue\'s base of operations in the Atlantis excavation zone. Your submarine is docked ahead', 'nothing useful here.') 
cave = ('Underwater Cave', 'You have entered the mouth of an underwater cave with your sub.', 'nothing useful here.') 
cemetery = ('Cemetery Chamber', 'You are in a large chamber within the cave. This seems to be a cemetery. There are symmetrically lined mounds of dirt, with obelisks at the head.', 'nothing useful here.') 
city_gate = ('City Gate', 'You stand at a crossroad of sorts, at the bottom of an upward sloping ramp.', 'nothing useful here.') 
city_outskirts = ('City Outskirts', 'You find yourself just outside the city walls.', 'nothing useful here.') 
castle_outskirts = ('Rear of Castle Ruins', 'You are standing at the rear of the castle ruins. There is a layer of rubble blocking the way, but you can clearly see a passage leading inside. Perhaps you can devise a way to move it...', 'nothing useful here.') 
castle_inside = ('Inside the Grand Castle of Atlantis', 'You have made it inside of the castle. All the advanced knowledge of the Atlanteans is at your disposal.', 'nothing useful here.') 
city_block0 = ('Beginning of Main Avenue in City', 'You are standing at the beginning of the main avenue of the city.', 'nothing useful here.') 
ruins1 = ('Rubble of Dilapidated House', 'You are standing in the middle of the ruins of what seems to have been a house.', tonic) 
mystic_house = ('Mystic House', 'You are standing inside the city Mystic\'s house.', sTonic) 
city_block1 = ('Second Block in City', 'You have moved to the second block of the city\'s main avenue.', 'nothing useful here.') 
abandoned_house = ('Abandoned House', 'You are standing in the middle of an abandoned house.', eng_key) 
blacksmith_house = ('Blacksmith\'s House', 'You are standing in what seems to be a blacksmith\'s building. There is a furnace, iron ore, smith\'s tools and various components for making swords. No coal though...', 'nothing useful here. But with the right items, something can be created here...') 
city_block2 = ('Third Block in City', 'You have moved to the third block of the city\'s main avenue.', 'nothing useful here.') 
marketplace = ('Abandoned Marketplace', 'You are standing in the middle of an abandoned marketplace. There might be some useful items laying around...', coal) 
engineer_house = ('Engineer\'s House', 'You are standing in the engineer\'s house. There might be some useful items lying around...', bomb) 
castle_main = ('Castle Main Entrance', 'You are standing in front of the main entrance of a huge castle. The grand entrance is blocked off by massive amounts of rubble. There must be another way in...', 'nothing useful here.') 


# ITEMS 
# below are the items which may be added to the inventory 
items = { 
    coal: (engineer_house,), 
    eng_key: (engineer_house,), 
    bomb: (castle_inside,), 
    tonic: ('anywhere',), 
    sTonic: ('anywhere',) 
} 


# INTERACTIONS(location-based) 
# below is a dictionary of events. Each location has certain events which can only take place there. 
# interactions dictionary = {location: (use+item response, search response)} 
lEvents = {sub_base: (cave,), 
    cave: (sub_base, cemetery, city_gate), 
    cemetery: (cave, city_outskirts), 
    city_gate: (cave, city_outskirts, city_block0), 
    city_outskirts: (cemetery, castle_outskirts, city_gate), 
    castle_outskirts: (city_outskirts,castle_inside), 
    castle_inside: (castle_outskirts,), 
    city_block0: (city_gate, ruins1, mystic_house, city_block1), 
    ruins1: (city_block0,), 
    mystic_house: (city_block0,), 
    city_block1: (city_block0, abandoned_house, blacksmith_house, city_block2), 
    abandoned_house: (city_block1,), 
    blacksmith_house: (city_block1,), 
    city_block2: (city_block1, marketplace, engineer_house, castle_main), 
    marketplace: (city_block2,), 
    engineer_house: (city_block2,), 
    castle_main: (city_block2,) 
} 


# TRAVEL OPTIONS 
# Below is a dictionary outlining the possible places to travel to depending on where you are currently located, this peice is essential to the travel function 
travelOpt = { 
    sub_base: (cave,), 
    cave: (sub_base, cemetery, city_gate), 
    cemetery: (cave, city_outskirts), 
    city_gate: (cave, city_outskirts, city_block0), 
    city_outskirts: (cemetery, castle_outskirts, city_gate), 
    castle_outskirts: (city_outskirts,castle_inside), 
    castle_inside: (castle_outskirts,), 
    city_block0: (city_gate, ruins1, mystic_house, city_block1), 
    ruins1: (city_block0,), 
    mystic_house: (city_block0,), 
    city_block1: (city_block0, abandoned_house, blacksmith_house, city_block2), 
    abandoned_house: (city_block1,), 
    blacksmith_house: (city_block1,), 
    city_block2: (city_block1, marketplace, engineer_house, castle_main), 
    marketplace: (city_block2,), 
    engineer_house: (city_block2,), 
    castle_main: (city_block2,) 
} 


def eHouseAccess(action, location, eHouse): 
    if eHouse == 'locked': 
     print "The door is locked! You need to find a key for this door." 
     travel(location) 
    else: 
     location = travelOpt[location][action - 1] 
     travel(location) 


def cInsideAccess(action, location, cInside): 
    if cInside == 'blocked': 
     print "The path is blocked by rubble! You need to find a way to clear the rubble." 
     travel(location) 
    else: 
     location = travelOpt[location][action - 1] 
     travel(location) 


def travel(location): 
    while True: 
     print "You are in the", location[0]+"." 
     print location[1] 
     print 'You can travel to:' 

     for (i, t) in enumerate(travelOpt[location]): 
      print i + 1, t[0] 

     action = raw_input("Pick a destination, or enter 'menu' for the main menu: ") 
     if action == 'menu': 
      main_menu(location, inventory, items) 
     else: 
      action = int(action)  
     if travelOpt[location][action - 1] == engineer_house: 
      eHouseAccess(action, location, eHouse) 
     elif travelOpt[location][action - 1] == castle_inside: 
      cInsideAccess(action, location, cInside) 
     else: 
      location = travelOpt[location][action - 1] 


def main_menu(location, inventory, items): 
    travel = travel(location) # **this is line 133** 
    invtry = showInv(inventory) 
    use = use(items, inventory) 
    quit = exit(0) 
    while True: 
     print "You are in the", location[0] 
     menu_list = [('Travel', travel), ('Inventory', invtry), ('Use', use), ('Search', search), ('Map', map), ('Quit', quit)] 
     print "Choose one:" 
     for (num, t) in enumerate(menu_list): 
      print num + 1, t[0] 
     main_choice = int(raw_input("> ")) 
     action = menu_list[main_choice - 1] 
     action[1] 


def search(location): 
    pass 


def map(location): 
    pass 


def showInv(inventory): 
    if inventory == []: 
     print "Your inventory is empty" 
     inv = 'empty' 
     return inv 
    else: 
     for (num, i) in enumerate(inventory): 
      print num + 1, i 
     inv = inventory 
     return inv 

def use(items, inventory): 
    a = showInv(inventory) 
    if a == 'empty': 
     print "There is nothing to use." 
    else: 
     showInv(inventory) 
     uItem = int(raw_input("Choose an item to use: ")) 


location = sub_base 
inventory = [] 
eHouse = 'locked' 
cInside = 'blocked' 
hp = 20 

map = """ 
Key: 
    * = indicates a point of entry 
      ______ ______ 
      |Castle|Castle| 
      |Outsk-|  | 
      |irts   | 
     ___|**____|__**__| 
     | City | |  | 
     |Outsk-| | City | 
     | irts | |  | 
    _____|*____*|___|*_____| 
|  | |  | 
| Grave | | City | 
| Yard | | Gates | 
|_____**|__|*______| 
     |  | 
     | Cave | 
     |  | 
     |__**___| 
     |  | 
     | Sub- | 
     | Base | 
     |_______| 
""" 


cityMap = """ 
Key: 
    * = indicates a point of entry 
      ________ 
      |  | 
      | Castle | 
      |  | 
    ______|___**___|________ 
    |  | City | Engin- | 
    |Market| Block | eer | 
    |Place * 3 * House | 
    |______|___ ___|________| 
    |Aband-| City | Black- | 
    | oned | Block | smith | 
    |House * 2 * House | 
    |______|___**___|________| 
    |  | City |  | 
    |Rubble| Block |Mystic's| 
    |  * 1 * House | 
    |______|________|________| 
""" 


name = raw_input("Enter your name: ") 
print "Welcome to the Atlantis Excavation Zone, %s." % name 
print "Your first day on the job and we already have a new cave for you to map... LUCKY!" 
print "The DeepBlue team takes you down to the sub base. Time to get to work." 
main_menu(location, inventory, items) # **this is line 236** 

這裏是回溯：

Traceback (most recent call last): 
File "ex36_2.py", line 236, in <module> 
main_menu(location, inventory, items) 
File "ex36_2.py", line 133, in main_menu 
travel = travel(location) 
UnboundLocalError: local variable 'travel' referenced before assignment 

我以爲變量已在管線133缺少什麼我在這裏被分配？

Answer 1

第一行

travel = travel(location) 

隱痕的名字travel當地整個功能。該名稱的所有查找都會查找本地名稱，包括引用行右側的名稱。那時候，沒有賦予本地名稱的價值，但是，因此錯誤。有可能是一個全球性的名稱travel，但由於作爲本地名稱標識travel編譯器，它只會查看本地命名空間。爲局部變量使用不同的名稱。