Python Tkinter使用StringVar调用字典？

Question

I'm working with tkinter in python and I have an annoying bug that I can't seem to fix, although the answer is probably obvious.

I am trying to call a dictionary with a string, but for some reason I get the error: Type Error: unhashable type: StringVar. Here is a snippet of code with that issue:

from Tkinter import *
gpa = Tk()

weightsy = {'0': 2, '.1': 6, '.25':.2, '.5':.56, '.75':75, '1':12}
acadw = StringVar()
acadw.set(".1")
print (weightsy.get(acadw)) #Here is the issue; it should return the integer 6.

mainloop()

For extra info, if I remove the tkinter related code (such as the import, gpa = Tk(), StringVar, .set, mainloop()) it works, so I believe it is a tkinter related issue.

Answer 1

Just as you had to call set method of StringVar object, you also need to call get to retrieve the str data.

print weightsy[acadw.get()]

The dictionary doesn't know to convert your object into a string so it attempts to get the value associated with acadw . You get a TypeError rather than a KeyError since StringVar objects happen to be unhashable.