ex_hello.py

import patterns
import mywidgets
import time

class HelloFunctor(object):
    def __call__(self, observer):
        if observer.Subject.text == 'Hello World':
            observer.Subject.text = 'Goodbye World'
        else:
            observer.Subject.text = 'Hello World'

class QuitFunctor(object):
    def __init__(self):
        self.done = False
    def __call__(self, observer):
        self.done = True

factory = mywidgets.TkWidgetFactory()
hello_button = factory.button(text='Hello World')
quit_button = factory.button(text='Quit')
factory.window().contents = [
        hello_button,
        '\n',
        quit_button,
    ]

quit = QuitFunctor()
patterns.CallbackObserver(hello_button, HelloFunctor())
patterns.CallbackObserver(quit_button, quit)

while not quit.done:
    time.sleep(.1)

factory.do_quit() # FIXME: this seems out of place

Generated by GNU enscript 1.6.3.

ex_multiply.py

import patterns
import mywidgets
import time
from PIL import Image

def float_or_zero(x):
    try: return float(x)
    except: return 0.0

class UserInterface(object):
    def __init__(self, factory):
        self.input_a = factory.edit(text='0')
        self.input_b = factory.edit(text='0')
        self.result = factory.label(text='0')
        self.quit_button = factory.button(text='Quit')
        self.kill_gui_func = factory.do_quit

        factory.window().contents = [
            Image.open('i-want-gnu.png'),
            factory.table(contents = [
                [ 'this',           self.input_a ],
                [ 'times this',     self.input_b ],
                [ 'equals this',    self.result ],
              ]),
            '\n',
            self.quit_button,
          ]

class Facade(object):
    def __init__(self, gui):
        self.done = False
        self.gui = gui
        patterns.CallbackObserver(self.gui.input_a, self.input_updated)
        patterns.CallbackObserver(self.gui.input_b, self.input_updated)
        patterns.CallbackObserver(self.gui.quit_button, self.do_quit)
    def do_quit(self, subject):
        self.done = True
        self.gui.kill_gui_func()
    def input_updated(self, subject):
        a = float_or_zero(self.gui.input_a.text)
        b = float_or_zero(self.gui.input_b.text)
        self.gui.result.text = str(a * b)

def main():
    factory = mywidgets.TkWidgetFactory()
    gui = UserInterface(factory)
    facade = Facade(gui)
    while not facade.done:
        time.sleep(.2)

if __name__ == '__main__': main()

Generated by GNU enscript 1.6.3.