Eventos

Introducción

Los eventos permiten ejecutar funciones en paralelo mediante objetos de evento. En lugar de llamar a funciones o subprocesos uno tras otro, los eventos permiten registrar funciones y activarlas todas a la vez. Cada función registrada se ejecuta en su propio subproceso, lo que permite que el robot realice varias acciones simultáneamente, como hacer parpadear los TouchLED y conducir.

A continuación se muestra una lista de métodos y constructores disponibles:

• Event – Creates a new event object.

• broadcast – Triggers all registered functions in an event object to run in parallel.

• broadcast_and_wait – Triggers all registered functions in an event object and waits for them to finish before continuing.

• event – Registers a function to the event object, optionally with arguments.

Create an Event Object

The Event constructor is used to create an event object that manages function execution in separate threads.

Usage:
Event()

Parámetro	descripción
	Este constructor no tiene parámetros.

def dash_lines():
    # Move the pen up and down
    while True:
        pen.move(DOWN)
        wait(0.5, SECONDS)
        pen.move(UP)
        wait(0.5, SECONDS)

def main():
    # Set the event
    move_event = Event()
    move_event(dash_lines)
    # Draw the dash line while driving forward
    move_event.broadcast()
    drivetrain.drive_for(FORWARD, 1000, MM)

# VR threads — Do not delete
vr_thread(main)

Broadcast

broadcast triggers an event, starting all registered functions in separate threads. This method does not pause execution of any subsequent functions.

Usage:
my_event.broadcast()

parámetro	descripción
event	El nombre del objeto de evento creado previamente.

def dash_lines():
    # Move the pen up and down
    while True:
        pen.move(DOWN)
        wait(0.5, SECONDS)
        pen.move(UP)
        wait(0.5, SECONDS)

def main():
    # Set the event
    move_event = Event()
    move_event(dash_lines)
    # Draw the dash line while driving forward
    move_event.broadcast()
    drivetrain.drive_for(FORWARD, 1000, MM)

# VR threads — Do not delete
vr_thread(main)

Broadcast and wait

broadcast_and_wait starts an event but waits for all registered functions to finish before continuing with subsequent functions.

Usage:
my_event.broadcast_and_wait()

parámetro	descripción
event	El nombre del objeto de evento creado previamente.

def move_and_turn():
    # Drive forward and turn
    drivetrain.drive_for(FORWARD, 150, MM)
    drivetrain.turn_for(RIGHT, 90, DEGREES)

def main():
    # Wait for the event to finish after 3 seconds
    move_event = Event()
    move_event(move_and_turn)
    while True:
        if brain.timer_time(SECONDS) > 3:
            move_event.broadcast_and_wait()
            break
        wait(5, MSEC)
    brain.print("Movement done.")

# VR threads — Do not delete
vr_thread(main)

Register Functions to an Event

Cuando se registra una función en un evento, se ejecutará en un hilo separado cuando se transmita el evento.

Usage:
event(callback, args)

Parámetro	Descripción
event	El nombre del objeto de evento creado previamente.
callback	Una función que se define previamente para ejecutarse cuando se transmite el evento.

def dash_lines():
    # Move the pen up and down
    while True:
        pen.move(DOWN)
        wait(0.5, SECONDS)
        pen.move(UP)
        wait(0.5, SECONDS)

def main():
    # Set and call the event and start driving
    move_event = Event()
    move_event(dash_lines)
    move_event.broadcast()
    drivetrain.drive(FORWARD)

# VR threads — Do not delete
vr_thread(main)