Tkinter Menu command

[Fredrik Lundh]

Raimo Tuisku wrote:

> Is it possible to pass arguments to a method which is executed after
> event? I am trying to do so with add_command method from Menu
> widget to avoid writing separate method for every case.
> #From class App:
>     self.mb = Menubutton(self.frame, text="Color")
>     self.mb.grid()
>     self.mb.menu = Menu(self.mb,tearoff=0)
>     self.mb['menu'] = self.mb.menu
>     self.colors=['red','green','blue']
>     for item in self.colors:
>         self.mb.menu.add_command
>         (label=item,command=lambda :self.set_color(item))
>     # Even this doesn't work. Apparently it always uses
>     # self.set_color('blue'). (self.label colors to blue)

    for item in self.colors:
        self.mb.menu.add_command
            (label=item,command=lambda :self.set_color(item))

when the lambda is called, its body will pick up the *current*
value of the "item" variable.  (it's a reference to something that
lives in another namespace, not a reference to its value)

to get the value it had when you created the lambda, you
need to use explicit name binding:

        self.mb.menu.add_command(
            label=item,
            command=lambda item=item:self.set_color(item)
        )

</F>