[Tkinter-discuss] validating an entry

[Jeff Cagle]

So it turned out that validating was not too hard, but you had to Google 
for the documentation.  Your name, Cameron, showed up a couple of times...

Here's the code:

# Testing an edit box with validation

from Tkinter import *


class MyEntry(Entry):

    def __init__(self, master, maxchars):
        Entry.__init__(self, master, validate = "key", 
validatecommand=self.validatecommand)
        self.MAX = maxchars

    def validatecommand(self, *args):
        return len(self.get()) < self.MAX 


if __name__ == '__main__':
    tkmain = Tk()
    e = MyEntry(tkmain, 5)
    e.grid()
    tkmain.mainloop()

The validatecommand has to return a Boolean.  I have no idea of the 
following, and haven't been able to find answers yet online:

1) what args are passed to validatecommand?  Obviously *args scoops them 
up, but would one ever want to use them?
2) what values other than "key" are acceptable to validate?

Thanks,
Jeff Cagle