Is this a function decorator?

I've just started playing around with pyglet.

In the first demo, I ran accross code like this:

window = pyglet.window.Window()

@window.开发者_运维知识库event
def on_draw():
    window.clear()
    label.draw()

I understand that this registers an event handler, but I don't understand how.

How could this be rewritten without the '@' syntax?

It's called an "event decorator." Yes, you could just write

window.on_draw = on_draw

after the "def on_draw()" definition, without using the decorator; but then if the window already had an on_draw, it would be overwritten. The decorator will "chain" multiple event handlers together.

According to the docs, Window.event is a decorator. Decorators can be simply added via using an @.