Python TypeError: 'NoneType' 对象不支持项目分配？
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TypeError: 'NoneType' object does not support item assignment?
提问by Kosig
So I start a root screen with a "file select" and a "go" button. The go button is disabled and I want to make it active after the file has been selected. When I select the file go should become active but instead this error "TypeError: 'NoneType' object does not support item assignment" Here is some sample code
所以我用一个“文件选择”和一个“开始”按钮启动一个根屏幕。转到按钮已禁用，我想在选择文件后将其激活。当我选择文件时，go 应该变为活动状态，而是出现此错误“TypeError: 'NoneType' object does not support item assignment” 这是一些示例代码
import Tkinter
import tkFileDialog
def chooseDir():
dir1=tkFileDialog.askopenfilename(parent=root, title='choose file path')
go['state']=Tkinter.ACTIVE
root=Tkinter.Tk()
global go
go=Tkinter.Button(text='file location',command=chooseDir,state=Tkinter.DISABLED).pack()
root.mainloop()
采纳答案by Keith
This line:
这一行：
go=Tkinter.Button(text='file location',command=chooseDir,state=Tkinter.DISABLED).pack()
is creating a temporary object, then calling pack() on it. The pack method returns None, so gois assigned None.
正在创建一个临时对象，然后对其调用 pack()。pack 方法返回 None，因此go被分配了 None。
Remove the .pack() then gowill be the Button object. Then call go.pack().
删除 .pack() 然后go将是 Button 对象。然后调用go.pack()。
回答by Daniel DiPaolo
(update for new error)
godoesn't exist in that scope, you'll need to get access to it somehow, or by using the one in the global scope using global goinside the chooseDirmethod perhaps
（更新新错误）
go在该范围内不存在，您需要以某种方式访问它，或者通过global go在chooseDir方法内部使用全局范围中的那个
Tkinter.Buttons don't behave like dictionaries, you can change their status via the config()method.
Tkinter.Buttons 的行为不像字典，您可以通过config()方法更改它们的状态。
Try:
尝试：
go.config(state=Tkinter.ACTIVE)
