Partial Function Application -- Advantages over normal function?

Mon Jul 18 16:17:28 EDT 2011

On 7/18/2011 3:23 PM, woooee wrote:
> Partial can be used in a GUI program, like Tkinter, to send arguments
> to functions. There are other ways to do that as well as using
> partial. The following program uses partial to send the color to the
> change_buttons function.
> from Tkinter import *
> from functools import partial
>> class App:
> def __init__(self, parent):
> self.my_parent = parent
> self.my_parent.geometry("200x100+10+10")
>> self.R = list()
> for ctr, color in enumerate(("Red", "Blue", "Green")):
> btn = Radiobutton(self.my_parent, text=color, value=ctr+1,
> command=partial(self.change_buttons, color))
> btn.grid(row = 2, column = ctr+1)

This is a nice illustration. For future reference: enumerate now takes a 
start value as second parameter. Given as 1, you do not need to remember 
to add 1 for each usage.
 for ctr, color in enumerate(("Red", "Blue", "Green"),1):
 btn = Radiobutton(self.my_parent, text=color, value=ctr,
 command=partial(self.change_buttons, color))
 btn.grid(row = 2, column = ctr)
> btn.deselect()
> self.R.append(btn)
> self.R[0].select()
> self.change_buttons("Red")
>> def change_buttons(self, color):
> self.my_parent.configure(bg=color)
> for btn in self.R:
> btn.configure(bg=color)
>> if __name__ == "__main__":
> root = Tk()
> root.title ("Color Option")
> app = App(root)
> root.mainloop()

-- 
Terry Jan Reedy