[Tutor] Shortening the code

[ALAN GAULD]

> > and text in your data list and configure each button directly:
> Is there any difference between a list and a data list?

Not really, but a list can handle any kind of data, even functions, 
objects etc (but they are all types of data too)
I was just being specific that I meant the list of data used to
configure your widgets. I should probably just have used its name!

###################
import tkinter as tk
from functools import partial

def button_clicked(button):
    if button["bg"] == "green":
        button.configure(bg="red")
    else:
        button.configure(bg="green")

class Window(tk.Frame):
    def __init__(self, master):
        super (Window, self).__init__(master)
        self.grid()
        self.create_widgets()

    def create_widgets(self):
        list_chair=[(0, 0, '01'), (0, 1, '02'),
                  (0, 3, '03'), (0, 4, '04'),
                  (1, 0, '05')]
        for row, column, name in list_chair:
            command = partial(button_clicked, button)
            button = tk.Button(self, color='green',
                            command=command, text=name)
            button.grid(row=row, column=column)

root = tk.Tk()
root.title("Test")
root.geometry("200x200")
app = Window(root)
root.mainloop()
######################

> However, nothing happens when I run the program.

Really? I get an error:

Traceback (most recent call last):
  File "/home/alang/src/Python/chairs.py", line 32, in <module>
    app = Window(root)
  File "/home/alang/src/Python/chairs.py", line 14, in __init__
    self.create_widgets()
  File "/home/alang/src/Python/chairs.py", line 21, in create_widgets
    command = partial(button_clicked, button)
UnboundLocalError: local variable 'button' referenced before assignment

Which correctly reports that you are using button before it is created.
There is also a bug in that the color parameter should, of course, 
be bg...

When I change create_widgets() to:

     def create_widgets(self):
        list_chair=[(0, 0, '01'), (0, 1, '02'),
                  (0, 3, '03'), (0, 4, '04'),
                  (1, 0, '05')]
        for row, column, name in list_chair:
            button = tk.Button(self, bg='green',
                               text=name)
            button['command'] = partial(button_clicked, button)
            button.grid(row=row, column=column)

It works as expected
 Alan Gauld
Author of the Learn To Program website
http://www.alan-g.me.uk/
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