Python EXEC Statement

ranger_nemo · 07-21-2003, 06:09 PM

Anybody know how to use the Python exec statement? I'm working on a GUI, and need to change the colors/states of a number of buttons when one is pushed. If I print cmd instead of exec, the lines come out right.

Code:

  buttons = [('nw', 'black'),
             ('n',  'black'),
             ('ne', 'red'),
             ('w',  'black'),
             ('e',  'black'),
             ('sw', 'black'),
             ('s',  'black'),
             ('se', 'black')]
  for (dir, clr) in buttons:
    cmd = "wd_" + dir + "_button.config(color='" + clr +"')"
    exec cmd

When run, I get the error...

Code:

Traceback (most recent call last):
  File "/usr/lib/python2.2/lib-tk/Tkinter.py", line 1316, in __call__
    return apply(self.func, args)
  File "weather2.py", line 58, in wd_ne
    exec cmd
  File "<string>", line 1, in ?
  File "/usr/lib/python2.2/lib-tk/Tkinter.py", line 1109, in configure
    self.tk.call((self._w, 'configure')
TclError: unknown option "-color"

I'm looking for a better way then writing out...

Code:

wd_nw_button.config(color='black')

...eight times, and five similar lines to change states on air_pressure buttons, and five similar lines to change states for pressure_change buttons, for each of the eight wind_directions. What is that...? Nearly 160 lines?

Proud · 07-22-2003, 02:50 PM

Maybe try checking the Documentation, specifically code or cmd ?

A better way may be to change your algorithm. Maybe keep a tract of current_red_button and pushed_button, and only change their colours around.
Or alter the button pushed event responce to something like reset_all_buttons(), make_button_red(this).

That's some really fast bad pseudo code btw

Strike · 07-24-2003, 01:21 PM

Yeah, your approach is bad (actually it sucks, but I don't want to say that as it sounds kinda negative

). Don't worry, I used to want to do that sort of thing as well.

The real solution you want is to store the buttons themselves in a dict.

Code:

wd_buttons = {'nw': Button('nw'), 'n': Button('n'), ... }

(note: I don't know how you create those buttons, but whatever you do to create them is represented by the Button() calls above.)

Then your code above simply becomes:

Code:

  buttons = [('nw', 'black'),
             ('n',  'black'),
             ('ne', 'red'),
             ('w',  'black'),
             ('e',  'black'),
             ('sw', 'black'),
             ('s',  'black'),
             ('se', 'black')]
  for (dir, clr) in buttons:
    wd_buttons[dir].config(color=clr)

ranger_nemo · 07-24-2003, 08:31 PM

Turns out, it's even easier...

Code:

buttons = [(wd_nw_button, 'black'),
           (wd_n_button,  'red'),
           (wd_ne_button, 'black'),
           (wd_w_button,  'black'),
           (wd_e_button,  'black'),
           (wd_sw_button, 'black'),
           (wd_s_button,  'black'),
           (wd_se_button, 'black')]
for (dir, clr) in buttons:
  dir.config(fg=clr)     # or... dir["fg"] = clr

This is my first GUI program, so I knew it would be ugly. I finally found it in the Tkinter module doc.

Of course, I had already implemented a way like Proud had suggested... Each button push first calls a function that turns all the buttons black, then turns the one pushed red. Only need to write out the color='black' lines once.

I still might use the idea above though, so I can pass any button_name, attribute, and setting to a function. Such as ... button_config(ap_hi_button, state, NORMAL)