[pygame] UI Blues

[Kris Schnee <kschnee@xxxxxxxxxx>]

In revisiting my interface code, in light of what I've learned from the 
tactics-game project, I've hit a snag.

Earlier, I'd set up my interface so that hitting a button or something 
would cause the button to call a "Notify" function of the main game 
object, sending it a dictionary describing what happened. 
{"headline":"click","sender":self} That meant having a special event 
queue in the game object, to be added to by Notify and read by a game 
loop. That is:

-In Screen X, there's an interface. The user hits a button.
-The button calls Notify.
-The loop for Screen X sees that an "Button B was clicked" message has 
appeared, and reacts to that.

That's the "poorly-formatted random data" situation I was trying to 
avoid, but I don't see how it _can_ be avoided. With the tactics game I 
was getting around it by having ad-hoc variables attached to the 
game-world object, rather than a generic message queue.

Another approach to UI handling I've had suggested is to have a double 
event-handling system. The first part handles raw Pygame events and adds 
to a queue of _gameplay_ events, to which the UI can also add. The 
second part handles the gameplay events, like so:

for event in pygame.event.get():
    if event.type == KEYDOWN and event.key == KEYS_JUMP:
        self.game_events.append("jump")

for event in self.game_events:
    if event == "jump":
        self.player.Jump()
    elif event == "pause_button_clicked":
        self.Pause()

Does this setup make any sense?