"export" 从函数到全局变量的元组

Question

我编写了一个函数，使用 Tkinter 提取列表框中的选定选项。打印命令只有在我直接在函数中编写时才有效。如何在函数外打印元组？

这是失败代码：

Traceback (most recent call last):
  File "C:/Users/....", line 68, in <module>
    print (selection)
NameError: name 'selection' is not defined

我试图将元组转换为全局变量。


    def doStuff():
        global selected
        selected = lb.curselection()
        if selected: # only perform  if user made a selection
            for index in selected:
                selection = (lb.get(index))# how you get the value of the selection from a listbox
    print(selection)
    ```

Answer 1

在函数内部设置的变量只能从函数内部访问。您需要将 return selection 添加到函数的末尾，然后执行 print(doStuff())

https://www.w3schools.com/python/python_functions.asp

Answer 2

您可以像下面这样在函数范围之外访问 selection。但请记住在函数范围外打印 selection 变量之前调用 doStuff() 函数。

selected = None 
selection = None

def doStuff():
        global selected, selection
        selected = lb.curselection()
        if selected: # only perform  if user made a selection
            for index in selected:
                selection = (lb.get(index))# how you get the value of the selection from a listbox
print(selection)

"export" 从函数到全局变量的元组

"export" a tuple from function to a global variable

python

listbox

python-2.7

python-3.x