Key binding not responding in tkinter

Question

I'm trying to bind the <Return> key event on two Entry but the validation code isn't working (there's no displayed error, the validate function just doesn't apply)

Here's the entry initialization :

from tkinter import *

fi = Tk()
l_n = Entry(fi)
l_t = Entry(fi)
b1 = Button(fi, cursor="hand2", overrelief=GROOVE, text="Run", command=someUnrelatedFunction, state=DISABLED)

And here's the code that is suppopsed to bind the validation function to the entries :

l_n.bind("<Return>",lambda name='l_n':validate(name))
l_t.bind("<Return>",lambda name='l_t':validate(name))

Finally, here's the packing and the validation function :

l_n.pack()
l_t.pack()

def validate(name):
    global v1,v2,n,t
    if name=='l_n':
        v1=True
        s=l_n.get()
        n=int(s)
        l_n.delete(0,END)
    elif name=='l_t':
        v2=True
        s=l_t.get()
        t=float(s)
        l_t.delete(0,END)
    if v1==True and v2==True:
        b1.config(state=NORMAL)

What's the problem here ?

Answer 1

In tkinter, when you do the binding, tkinter itself adds another argument to the callback that holds information of the event. So when you are are trying to pass parameters with lambda, you should consider that as well.

l_n.bind("<Return>", lambda event, name='l_n': validate(name))
l_t.bind("<Return>", lambda event, name='l_t': validate(name))