Re: [pygame] timer callback into object?

Hey ya,

so... a few ways.

# First threading. It's not so quick with threads, and delay can be longer than you hope.
# https://docs.python.org/3/library/threading.html#threading.Timer
from threading import Timer
def hello():
print("hello, world")
seconds = 1.0
Timer(seconds, hello).start()

# secondly, add event handling to your scene graph.

I usually like to have all my objects able to accept events. But as you say, it takes a bit of work to wire it through to everything. I make all my objects have a similar signature (like sprites for example), and then add a handle_events to all of them.

# thirdly, You can use the event queue, register callbacks anywhere, but process callbacks in your main loop.

# store a list of callbacks somewhere.

mainmodule.callbacks = []

# then add event processors anywhere in your app.

def process_events(events):

print('deep inside a nest of functions')

mainmodule.callbacks.append(process_event)

# in your main event loop.
for cb in mainmodule.callbacks:

cb(events)

# when your code doesn't want the event handler any more.

mainmodule.callbacks.remove(process_event)

ps. You should totally try python3! It's sooooo much more elegant :)

On Sat, Feb 11, 2017 at 2:30 AM, Irv Kalb <Irv@xxxxxxxxxxxxxx> wrote:

I've been working on porting a game that I wrote in a different language/environment, and I want to make the Python/PyGame code as efficiently as possible.

I have code in an object, that triggers an event that should occur, say 1 second later. I used pygame.set_timer, created an ID and set 1000 milliseconds. However, in order to catch that event, I need to have code in my main loop, which passes down knowledge of that event (potentially through several layers of objects), all the way back down to my object that created the timer. I have this working, but it doesn't feel like a very clean implementation.

As another very simple example, imagine that I wanted to make a generic animation object that would run an animation off of a list of images at some given speed (independent of the frame rate). Ideally, I want to have a timer that tells the current instance of the animation object to change to the next image - directly. It seems like this type of thing should be easy within a single class, but in practice, as I said, I have had to add code to several layers to get notification back to animation object(s) where I really want to get notification.

So, my specific question is this: Is there any way for an object to create a timer, that results to a callback within the same object?

If not, I guess one way to do this would be to have a central Timer Manager object that I could call to set up a timer, and pass it a timer ID, amount of time to wait, (just like a call to set_timer), but also pass in a reference to the current object (self), and a method name to call back (maybe "animate"). Then, in the main loop, I could call the Timer Manager with all events, it would check if the event ID matched any it should be looking for, and if so, call the appropriate method of the given object. I'm sure I could make it work, but I'm wondering if I am missing something simple.

Thanks in advance,

Irv

PS: Still in Python 2, but I am seriously looking into potentially porting code to Python 3. In fact, I had a talk with my manager at one of my colleges today about it.