Question

在包含创建新对象的方法时，我对导入方法感到困惑。我很难解释，因为我仍然在学习语言，但这是一个正在发生的事情的例子。

我有macrocalc.py

from interface import Interface

def main():
    a = Interface();
    print "Welcome!"
    print "!hat would you like to do?"
    a.display_options()

if __name__ == "main":
    main()

稍后在我的代码中，我使用from marcocalc import main导入main。然后我运行main()方法。但是我得到了错误：

  File "macrocalc.py", line 1, in <module>
    from interface import Interface
  File "/Users/username/Development/foodcalc/interface.py", line 1, in <module>
    from addFood import addfood
  File "/Users/username/Development/foodcalc/addFood.py", line 2, in <module>
    from macrocalc import main
  File "/Users/username/Development/foodcalc/macrocalc.py", line 1, in <module>
    from interface import Interface
ImportError: cannot import name Interface

我的interface.py：

from addFood import addfood

class Interface:
    #options = ["1 - create a meal plan","2 - add food","3 - look up food"]

    def display_options(self):
        options = ["1 - create a meal plan","2 - add food","3 - look up food"]
        for choice in options:
            print choice

        selection = int(raw_input())
        if selection > 3:
            print "Incorrect selection. Please try again."
            self.display_options()
        else: 
            print "You chose: ",
            if selection == 1:
                print "\'create a meal plan\'"

            elif selection == 2:
                print "\"add food\""
                addfood()

            else: 
                print "\"look up food\""

我尝试添加行from interface import Interface，但错误仍然存在。

如果需要更多代码。我会把它添加到帖子中。请让我知道

Answer 1

您已经介绍了可怕的循环依赖。

在macrocalc.py，第1行：

# Call this A
from interface import Interface

在interface.py，第1行：

from addFood import addfood

在addFood.py，第2行：

from macrocalc import main

但现在我们又回到了A！

你必须重构你的程序，所以它不会这样做。：）

Answer 2

您已创建导入循环：

File "macrocalc.py", line 1, in <module>
    from interface import Interface
  File "/Users/username/Development/foodcalc/interface.py", line 1, in <module>
    from addFood import addfood
  File "/Users/username/Development/foodcalc/addFood.py", line 2, in <module>
    from macrocalc import main
  File "/Users/username/Development/foodcalc/macrocalc.py", line 1, in <module>
    from interface import Interface
ImportError: cannot import name Interface

看看如果没有错误会发生什么，代码就像你写的一样完成：

界面导入addFood
addFood导入macrocalc
macrocalc进口界面
界面导入addFood
addFood导入macrocalc
macrocalc进口界面

...

您需要在某处删除import语句以防止无限循环导入。

导入创建新对象的方法

2 个答案: