Python 在多个函数中使用相同的列表/字典

我是python新手，目前仍在学习hwo处理列表和字典

我有这两个功能

    def food_database(item_name, size_serv, calorie_serv, protein_serv, carb_serv, fat_serv):
      # used to list the different foods when users ask for it
      # food database
      food_dict = [ {
        'food_name': item_name,
        'serving_size': size_serv,
        'serving_calorie': calorie_serv,
        'serving_protien': protein_serv,
        'serving_fat': fat_serv,
        'serving_carb': carb_serv
        } ]
      print food_dict

    def food_in_diet(item_name, size_serv, calorie_serv, protein_serv, carb_serv, fat_serv, num_serv):
        # used to show how much is in the diet plan for the user
      User_diet_dict = [ {
        'food_name': item_name,
        'amount': num_serv*size_serv,
        'serving_calorie': num_serv*calorie_serv,
        'serving_protien': protein_serv,
        'serving_fat': fat_serv,
        'serving_carb': carb_serv
        } ]
      print User_diet_dict

我有另一个功能

    def add_food():
      ask_to_add_another = raw_input("Would you like to add another food?(y/n)")
      if ask_to_add_another == 'y':
        # update
        item_name = raw_input("What is the name of the food you would like to add? ")
        size_serv = input("What is the size(grams) in each serving of %s? " % item_name)
        calorie_serv = input("How many calories is in each serving of %s? " % item_name)
        protein_serv = input("How many grams of protein is in each serving of %s? " % item_name)
        carb_serv = input("How many grams of carbohydrates is in each serving of %s? " % item_name)
       fat_serv = input("How many grams of fat is in each serving of %s? " % item_name)
        num_serv = input("How many servings of %s would you like to add? " % item_name)

        food_dict.append( {
          'food_name': 'item_name',
          'serving_size': size_serv,
          'serving_calorie': calorie_serv,
          'serving_protien': protein_serv,
          'serving_fat': fat_erv,
          'serving_carb': carb_serv
        } )

    #    User_diet_dict.append = ( {
    #      'food_name': item_name,
    #      'amount': num_serv*size_serv,
    #      'serving_calorie': num_serv*calorie_serv,
    #      'serving_protien': protein_serv,
    #      'serving_fat': fat_serv,
    #      'serving_carb': carb_serv
    #    } )
        # add to the dictonary/list
        print food_dict
        add_food()
      if ask_to_add_another == 'n':
        return False

函数的作用是：更新食物字典并添加到列表中

我得到了错误

    Traceback (most recent call last):
      File "MACROCALC.py", line 156, in <module>
        main()
      File "MACROCALC.py", line 35, in main
        add_food()
      File "MACROCALC.py", line 130, in add_food
        food_dict.append( {
    NameError: global name 'food_dict' is not defined

回溯（最近一次呼叫最后一次）：
文件“MACROCALC.py”，第156行，在
main（）
文件“MACROCALC.py”，第35行，主
添加食物（）
文件“MACROCALC.py”，第130行，添加食物
食物目录附加（{
名称错误：未定义全局名称“食品目录”

我觉得这似乎是因为字典不是全球性的

如果有人好奇-->

开放的建议！Noob程序员期待变得更好

---

感谢您的帮助！

在每个子程序中添加以下内容-

global food_dict

---

将

food\u dict

声明为

global

，放在每个将改变列表的函数的顶部。对于

列表

来说，改变基本上是赋值，而不是使用

append（）

。通常，使用类的方法并不构成我上面描述的改变。见下文：

def init():
    global food_dict
     # assignment is manipulation
    food_dict = [{'name': 'apple'}, {'name': 'orange'}]

def next():
    # notice no 'global' usage but this still works
    food_dict.append({'name': 'kiwi'})

def lastly():
    global food_dict
    # assign to empty list
    food_dict = [{}]

>>> init()
>>> print food_dict
[{'name': 'apple'}, {'name': 'orange'}]
>>> next()
>>> print food_dict
[{'name': 'apple'}, {'name': 'orange'}, {'name': 'kiwi'}]
>>> lastly()
>>> print food_dict
[{}]

---

这是因为

food\u dict

不在

add\u food

的范围内。解决这一问题的一种方法是将其全局化，但更好的方法是将这些

print

s更改为

return

s，调用

food\u数据库

，并将其输出存储在一个变量中。