classmethod for Tkinter-Monitor-Window

Question

Hello together,

I would like to realise a monitor window that reports the user about ongoing computations. To do so I wrote a little class. But as I would like to use it accross different modules in an easy fashion I thought to implement it with classmethods. This allows to use it in the following way without instances:

from MonitorModule import Monitor
Monitor.write("xyz")

Also, if I use it in an other module, the output of Monitor.write() within other_module.py will be displayed in the same window.

This I can import in each module to redirect specific outputs to the same monitor. I got it to work except one little thing that I don't understand. I can't close the Monitor-window with the specific handler that I wrote. I could do it with the non-classmethod-way but not with the handler as a classmethod.

Look at the code:

import Tkinter
class Monitor_non_classmothod_way(object):
  def __init__(self):
    self.mw = Tkinter.Tk()
    self.mw.title("Messages by NeuronSimulation")
    self.text = Tkinter.Text(self.mw, width = 80, height = 30)
    self.text.pack()
    self.mw.protocol(name="WM_DELETE_WINDOW", func=self.handler)
    self.is_mw = True
  def write(self, s):
    if self.is_mw:
      self.text.insert(Tkinter.END, str(s) + "\n")
    else:
      print str(s)
  def handler(self):
    self.is_mw = False
    self.mw.quit()
    self.mw.destroy()

class Monitor(object):
  @classmethod
  def write(cls, s):
    if cls.is_mw:
      cls.text.insert(Tkinter.END, str(s) + "\n")
    else:
      print str(s)
  @classmethod
  def handler(cls):
    cls.is_mw = False
    cls.mw.quit()
    cls.mw.destroy()
  mw = Tkinter.Tk()
  mw.title("Messages by NeuronSimulation")
  text = Tkinter.Text(mw, width = 80, height = 30)
  text.pack()
  mw.protocol(name="WM_DELETE_WINDOW", func=handler)
  close = handler
  is_mw = True

a = Monitor_non_classmothod_way()
a.write("Hello Monitor one!")
# click the close button: it works
b = Monitor()
Monitor.write("Hello Monitor two!")
# click the close button: it DOESN'T work, BUT:
# >>> Monitor.close()
# works...

So, the classmethod seems to work and also seems to be accessible in the right way! Any idea, what went wrong, that it doesn't work with the button?

Cheers, Philipp

Answer 1

You don't need lots of classmethods just to make it easy to use an object across multiple modules.

Instead consider making an instance at module import time as shown here:

import Tkinter

class Monitor(object):

  def __init__(self):
    self.mw = Tkinter.Tk()
    self.mw.title("Messages by NeuronSimulation")
    self.text = Tkinter.Text(self.mw, width = 80, height = 30)
    self.text.pack()
    self.mw.protocol(name="WM_DELETE_WINDOW", func=self.handler)
    self.is_mw = True

  def write(self, s):
    if self.is_mw:
      self.text.insert(Tkinter.END, str(s) + "\n")
    else:
      print str(s)

  def handler(self):
    self.is_mw = False
    self.mw.quit()
    self.mw.destroy()

monitor = Monitor()

other_module.py

from monitor import monitor
monitor.write("Foo")