Python: Getting option from function?

问题

I'm working with Tkinter in Python and am using OptionMenu and want to get the selection the user makes.

ex1 = StringVar(root)
ex1.set("Pick Option")
box = OptionMenu(root, "one","two","three", command=self.choice)

def choice(self,option):
   return choice

It work when I just do:

print choice

But I though I could somehow return it and then store it in a variable. For example, at the start of the code I made:

global foo
foo = ""

and then tried:

def choice(self,option):
   foo = option
   return foo

But this didn't work. Does anyone know where I am going wrong? Thanks.

回答1:

This works, but not sure it is what you wanted.

from Tkinter import StringVar
from Tkinter import OptionMenu
from Tkinter import Tk
from Tkinter import Button
from Tkinter import mainloop

root = Tk()
ex1 = StringVar(root)
ex1.set("Pick Option")
option = OptionMenu(root, ex1, "one", "two", "three")
option.pack()


def choice():
    chosen = ex1.get()
    print 'chosen {}'.format(chosen)
    # set and hold using StringVar
    ex1.set(chosen)
    root.quit()
    # return chosen


button = Button(root, text="Please choose", command=choice)
button.pack()
mainloop()
# acess the value from StringVar ex1.get
print 'The final chosen value {}'.format(ex1.get())

回答2:

The question is an example of why it is suggested that you learn classes first and use them to program a GUI https://www.tutorialspoint.com/python3/python_classes_objects.htm

import sys
if 3 == sys.version_info[0]:  ## 3.X is default if dual system
    import tkinter as tk     ## Python 3.x
else:
    import Tkinter as tk     ## Python 2.x

class StoreAVariable():
    def __init__(self, root):
        self.root=root
        self.ex1 = tk.StringVar(root)
        self.ex1.set("Pick Option")
        option = tk.OptionMenu(root, self.ex1, "one", "two", "three")
        option.pack()

        tk.Button(self.root, text="Please choose", command=self.choice).pack()

    def choice(self):
        self.chosen = self.ex1.get()

        ## the rest has nothing to do with storing a value
        print('chosen {}'.format(self.chosen))
        self.ex1.set(self.chosen)
        self.root.quit()
        # return chosen


root = tk.Tk()
RV=StoreAVariable(root)
root.mainloop()

print('-'*50)
print('After tkinter exits')
print('The final chosen value={}'.format(RV.chosen))

回答3:

Add global statement inside the method:

def choice(self,option):
   global foo
   foo = option

来源：https://stackoverflow.com/questions/48958535/python-getting-option-from-function

标签

python

user-interface

tkinter

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