Decorator Recipe: Event Binding in Tkinter

Step 2

Unlike other event handling mechanisms in Tkinter, “command” callbacks do not accept the target widget. This means that we can’t do something like this:

@btn1.command
@btn2.command
def onclick(target):
    print 'You clicked on button <%s>' % target['text']

Modify the MyButton.command method to make the above example work correctly.

from Tkinter import *

class MyButton(Button):
    def command(self, func):
        # Provide new logic here
        return func

if __name__ == '__main__':
    frame = Frame()
    frame.master.title("Event binding with decorators")
    frame.pack()

    btn1 = MyButton(frame, text="One")
    btn1.pack()

    btn2 = MyButton(frame, text="Two")
    btn2.pack()

    @btn1.command
    @btn2.command
    def onclick(target):
        print 'You clicked on button <%s>' % target['text']

    frame.mainloop()

Expected output:

Hints

1. You need to use a nested function (or a lambda).
2. Remember that the ‘command’ callback is not allowed to take any arguments. That means you need to use a closure.
3. Don’t forget the return value!
4. Your solution might contain the following expression: lambda: func(self).

Solution: solutions/tkinter2.py

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