New Demo - Dispatchers - from the Udemy course

DemoPrograms/Demo_Dispatchers.py

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+"""
+    Demo Dispatchers
+
+    Alternative to if/else event processing
+
+    Adapted from "The Official Python GUI Programming with PySimpleGUI Course"
+
+    Most PySimpleGUI demos follow the simple if-else event processing, but there are
+    other ways to process or dispatch events.
+
+    Event Dispatchers:
+        * If-Else
+        * Dictionaries
+        * Functions as keys
+
+    The handlers in this demo are all functions that are called once the event is detected
+
+    The dispatch dictionary maps from an event to a function.  It's more compact than a series
+    of if/else statements if you have a lot of different events and are handling events in functions
+
+    Keep it SIMPLE.  Add complexity as you need it.   If it is clearer to do the event processing in the
+    event loop rather than functions, then do it in the event loop.
+
+    http://www.PySimpleGUI.org
+    Copyright 2021 PySimpleGUI
+"""
+
+import PySimpleGUI as sg
+
+SYMBOL_X = '❎'
+SYMBOL_CHECK = '✅'
+
+
+##   ##   ##   #    # ####   #      ###### #####   ####
+##   ##  #  #  ##   #  #  #  #      #      #    # #    #
+##   ## #    # # #  #  #   # #      #      #    # #
+####### ###### #  # #  #   # #      ####   #####   ####
+##   ## #    # #   ##  #   # #      #      #  #        #
+##   ## #    # #    #  #  #  #      #      #   #  #    #
+##   ## #    # #    # ####   ###### ###### #    #  ####
+
+def do_go(window):
+    window['-STATUS-'].update(SYMBOL_CHECK, text_color='pink')
+
+def do_stop(window):
+    window['-STATUS-'].update(SYMBOL_CHECK, text_color='pink')
+
+def do_tuple(window):
+    window['-STATUS-'].update(SYMBOL_CHECK, text_color='pink')
+
+def do_other(window):
+    window['-STATUS-'].update(SYMBOL_CHECK, text_color='yellow')
+
+def do_simple(window):
+    window['-STATUS-'].update(SYMBOL_CHECK, text_color='yellow')
+
+def do_not_found(window):
+    window['-STATUS-'].update(SYMBOL_X, text_color='red')
+
+
+#    #   ##   ### #    #
+##  ##  #  #   #  ##   #
+# ## # #    #  #  # #  #
+# ## # ######  #  #  # #
+#    # #    #  #  #   ##
+#    # #    #  #  #    #
+#    # #    # ### #    #
+
+def main():
+    # --------- A Dispatch Dictionary -------
+    dispatch_dict = {'Go':do_go, 'Stop':do_stop, (1,2):do_tuple}
+
+    # --------- Define layout and create Window -------
+
+    layout = [[sg.Text('Dispatching Approaches')],
+              [sg.Text('Status:'), sg.Text(size=(3, 1), key='-STATUS-')],
+              [sg.Text(size=(50, 1), key='-OUT-')],
+              [sg.Button('Simple'), sg.Button('Go'), sg.Button('Stop'), sg.Button('Other', key=do_other),
+               sg.Button('Tuple', key=(1,2)), sg.Button('Bad')]]
+
+    window = sg.Window('Dispatchers', layout, font='Default 16', keep_on_top=True)
+
+    # --------- Event Loop -------
+    while True:
+        event, values = window.read()
+        if event == sg.WIN_CLOSED:      # Test for window closed (always do this one)
+            break
+
+        window['-OUT-'].update(f'Event = {event}')
+
+        # --------- Dispatching of events ---------
+        # Event processing.... a minimal if-else to show 3 dispatchers
+        if event == 'Simple':           # Dispatch using direct string compare
+            do_simple(window)
+        elif callable(event):           # Dispatch when event is a function
+            event(window)
+        elif event in dispatch_dict:    # Dispatch using a dispatch dictionary
+            func = dispatch_dict.get(event)
+            func(window)
+        else:                           # None of the above
+            do_not_found(window)
+
+    # --------- After event loop ---------
+    window.close()
+
+
+if __name__ == '__main__':
+    main()