python：合并按钮产生＆＃34;未定义＆＃34;

Question

我正在尝试在应用程序内部显示B4按钮，但它没有在其中显示并产生“B4未定义”

from tkinter import *
import tkinter
top = tkinter.Tk()
B1 = tkinter.Button(top, text ="circle", relief=RAISED,\
                         cursor="circle")
B2 = tkinter.Button(top, text ="plus", relief=RAISED,\
                         cursor="plus")
B3 = tkinter.Button(top, text=u"good !",relief=RAISED,\
                         cursor="plus")
def initialise(self):
    self.grid()                                
    B4 = tkinter.Button(self,text=u"Click me !",                                                              
                                command=self.OnButtonClick)
    button.grid(column=1,row=0)
def OnButtonClick(self):
    print( "You clicked the button" )
B1.pack()
B2.pack()
B3.pack()
B4.pack()
initialise()
top.mainloop()

Answer 1

您的问题是函数initialize的范围不会扩展到主程序。因此，B4未定义。

此外，您没有将任何内容传递给initialise。

相反，您可以将B4设为全局，也可以将其从函数中删除。

<强> global ：

from Tkinter import *
import Tkinter
global B4
top = Tkinter.Tk()
B1 = Tkinter.Button(top, text ="circle", relief=RAISED,\
                         cursor="circle")
B2 = Tkinter.Button(top, text ="plus", relief=RAISED,\
                         cursor="plus")
B3 = Tkinter.Button(top, text=u"good !",relief=RAISED,\
                         cursor="plus")
def initialise(self):
    global B4
    self.grid()
    B4 = Tkinter.Button(self,text=u"Click me !",
                                command=OnButtonClick(self))
    B4.grid(column=1,row=0)
def OnButtonClick(self):
    print( "You clicked the button" )

initialise(top)
B1.pack()
B2.pack()
B3.pack()
B4.pack()
#initialise()
top.mainloop()

---

运行方式：

bash-3.2 $
You clicked the button

功能之外：

from Tkinter import *
import Tkinter
top = Tkinter.Tk()
top.grid()
def OnButtonClick(self):
    print( "You clicked the button" )
B1 = Tkinter.Button(top, text ="circle", relief=RAISED,\
                         cursor="circle")
B2 = Tkinter.Button(top, text ="plus", relief=RAISED,\
                         cursor="plus")
B3 = Tkinter.Button(top, text=u"good !",relief=RAISED,\
                         cursor="plus")
B4 = Tkinter.Button(top,text=u"Click me !",                                                              
                                command=OnButtonClick(top))
B4.grid(column=1,row=0)


B1.pack()
B2.pack()
B3.pack()
B4.pack()
top.mainloop()

---

运行方式：

bash-3.2 $
You clicked the button

---

示例：

>>> def foo():
...     bar = 6
... 
>>> bar
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'bar' is not defined
>>>