Python + Tkinter and Python + Gtk

Remembering that Python was intended as a scripting language, compare these two HelloWorld from Python.

First, Tkinter for Tk as in Tcl/Tk

from Tkinter import *
root = Tk()

class HelloWorld:

def __init__(self):
  widget = Button(root, text = 'Hello World', command = self.quit)
  widget.pack()

def quit(self):

  print "Hello World"

  import sys

  sys.exit()

HelloWorld()
root.mainloop()

Now to compare the same minimal HelloWorld with Gtk.  First, install Gtk+  ( and on Windows XP  that means get all of the dependencies - the DLL's - on the path.)

import pygtk
pygtk.require('2.0')
import gtk

class HelloWorld:
def hello(self, widget, data=None):
print "Hello World"

def delete_event(self, widget, event, data=None):
print "delete event occurred"
return False

def destroy(self, widget, data=None):
   gtk.main_quit()

def __init__(self):
   self.window = gtk.Window(gtk.WINDOW_TOPLEVEL)
   self.window.connect("delete_event", self.delete_event)
   self.window.connect("destroy", self.destroy)
   self.window.set_border_width(10)
   self.button = gtk.Button("Hello World")
   self.button.connect("clicked", self.hello, None)
   self.button.connect_object("clicked", gtk.Widget.destroy, self.window)
   self.window.add(self.button)
   self.button.show()
   self.window.show()

def main(self):
   gtk.main()

if __name__ == "__main__":
    hello = HelloWorld()
    hello.main()

Whatever the merits of Gtk+ as a cross-platform C GUI framework for general purpose languages, something looks to have gone wrong with the Python library PyGtk.

Even with Tk itself, something comparable occurs when using Tk from Haskell versus using Tk from OCaml.  Probably  expect was the Tcl "killer app" but Tk is what most developers know of Tcl today.  Tk was also an early mainstay of Ruby.  Here is the HelloWorld demo using Gtk+ from the Ruby-Gnome team:

# Copyright (c) 2002,2003 Ruby-GNOME2 Project Team
require 'gtk2'

button = Gtk::Button.new("Hello World")
button.signal_connect("clicked") {
    puts "Hello World"
}

window = Gtk::Window.new
window.signal_connect("delete_event") {
    puts "delete event occurred"
#true
   false
}

window.signal_connect("destroy") {
   puts "destroy event occurred"
   Gtk.main_quit
}

window.border_width = 10
window.add(button)
window.show_all

Gtk.main

Now this is a little better, but compared to Ruby + Tk we are at almost double the lines of code.

To see a really elegant use of Tk, see the QTk framework for Oz, the language.  I'm fiddling with a QCurl variant for Oz just now.  I added some notes on OCaml and labltk over at wikia.com

QTk scripting in Oz/Mozart

The relative neglect of oz/mozart compared to say, Scala, has an explanation.

Part of it must lie in the needless snags along the learning curve. Steep is fine; jagged bits, less so.

There is no learning Oz/Mozart without embracing their emacs mode. And tolerating their tutorial.

Do not begin with applications. An application will require at least one 'functor'.

Ignore the bits that say you are compiling. You are not. No tutorial code will compile. Just do as you are told (follow the instructions) and 'feed' in a line. Or 'feed' in a region. Or 'feed' in a buffer.

What they mean is pass a line, a selection or the file through the interpreter only.

Think of it as scripting in Oz/Mozart. Now you can open a window with widgets using an few lines of Qtk.

No language which interfaces to Tk should be hampered by such a tutorial or such documentation; the usual answer is to buy the somewhat pricey MIT book by Peter van Roy.

Try to understand that the people who are assessing the need to revise the on-line documentation already know oz/Mozart inside-out and cannot 'see' the bits that say 'compile' when nothing compiled at all. They think you know what they mean by 'pickle' and that you get the 'functor' jibe at Prolog. A module is a module. Sometimes in some language a class is just a module. And writing a fine tutorial is an art. If you can get the video intro to Revolution/Transcript/MetaCard to run under Windows using the required QT codec, you may actually see what I mean.

But hey, you could not script the Oz/Qtk way in C. The fact that it looks easier in Jython may be that you know java and python. But it is easier in Tcl/Tk wish. So the point must be what can be achieved in oz/Mozart and that may be as much as can be achieved with Scala and then some.

Watch this blog for a link to a tutorial and a concordance/commentary to their friendly-looking documentation. And just accept that all you need to know is in the oz/Mozart maillist.

Somewhere in oz, climbing a cliff on the way to the corner store.

Note: do try the QTk Prototyper.  The tutorial leaves out one essential: declare the Prototyper, as in

 declare Prototyper

[Prototyper]={Module.link ["x-oz://system/wp/Prototyper.ozf"]}

{Prototyper.run}