Need help with Tkinter bind statement

[John Grayson]

-----Original Message-----


>  > Hello -
>  > I have been working on an RPN calculator program for a while now, and
>  > I am having problems with some bindings.  Here is a code snippet of
>  > where I'm having trouble:


Snip..


>  > The second problem is that when I
>  > use any of these keys, the keystroke shows up in the entry widget.
>  > What I want to happen is that pressing the "+" key, for example,
>  > should add the values in the xStack and yStack (which it does) and
>  > then put the result in the yStack entry widget (which it also does).
>  > The problem is that the "+" is left in the xStack.  The contents of
>  > the xStack are deleted by the Calc function, so I thought it would
>  > also delete the "+" as well.

>  > Thanks.

>  > Mike

Here is the solution to both your problems...

from Tkinter import *

root = Tk()

def gotit(which):
    print 'Got', which
    return "break"

frame = Frame(root)
entry = Entry(frame)
entry.pack(anchor=CENTER)
frame.pack()

entry.bind('<+>', lambda event, fxn = 'y+x':gotit(fxn))
entry.bind('<Key-minus>', lambda event, fxn = 'y-x':gotit(fxn))
entry.bind('<*>', lambda event, fxn = 'y*x':gotit(fxn))
entry.bind('</>', lambda event, fxn = 'y/x':gotit(fxn))

root.mainloop()


1) You've got to use <Key-minus> since "-" is a valid token
   in the bind...

2) return "break" stops the propagagation of the event to
   the widget, so it does not insert the character.



     John Grayson