Tkinter

[Fredrik Lundh]

"Jay" wrote:

> I wold like to be able to generate buttons from a list in a file.
> How would I go about making each button have a different command,
> Lets say make the button print its label instead of print "."
>
> The problem I have is I don't know what the list is going to be until
> it is opened or how big so I carnet make a def for each.

def is an executable statement, and creates a new function object
everytime it's executed.  if you want a new function for each pass
through a loop, just put the def inside the loop:

> from Tkinter import *
>
> class App:
>     def __init__(self, root):
>
>         self.DisplayAreaListsFrame = Frame(root)
>         self.DisplayAreaListsFrame.pack()
>
>         Lists = ["A1","B2","C3","D4"]
>
>         for i in Lists:

               def callback(text=i):
                   print text

>             self.DisplayAreaListButton = Button(
>                 self.DisplayAreaListsFrame,
>                 text=i,
>                 command=callback)
>             self.DisplayAreaListButton.pack(side=LEFT,padx=10)
>
> root = Tk()
> app = App(root)
> root.mainloop()

the only think that's a little bit tricky is scoping: you can access all
variables from the __init__ method's scope from inside the callbacks,
but the callbacks will be called after the loop is finished, so the "i"
variable will be set to the *last* list item for all callbacks.

to work around this, you have to explicitly pass the *value* of "i" to
to the callback; the "text=i" part in the above example uses Python's
default argument handling to do exactly that.

</F>