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介绍

Events allow you to run functions in parallel by using event objects. Instead of calling functions or threads one after another, events let you register functions and then trigger them all at once. Each registered function runs in its own thread, so your robot can do multiple things—like blinking LEDs and driving—at the same time.

Below is a list of available methods and constructors:

• Event – Creates a new event object.

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

• 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.

Create an Event Object

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

Usage:
Event()

范围	description
	此构造函数没有参数。

# Blink LEDs while moving forward
# Create move_event as an Event object
move_event = Event()

def blink_leds():
    while True:
        robot.led.on(ALL_LEDS, RED)
        wait(0.5, SECONDS)
        robot.led.on(ALL_LEDS, BLACK)
        wait(0.5, SECONDS)

move_event(blink_leds)
move_event.broadcast()
robot.move_at(0)

Register Functions to an Event

当您将一个函数注册到某个事件时，它将在事件广播时在单独的线程中执行。

Usage:
event(callback, args)

范围	描述
event	先前创建的事件对象的名称。
callback	先前定义的在事件广播时执行的函数。
args	Optional. A tuple containing arguments to pass to the callback function. See Using Functions with Parameters for more information.

# Blink LEDs while moving forward and turning
move_event = Event()

def blink_leds():
    while True:
        robot.led.on(ALL_LEDS, RED)
        wait(0.5, SECONDS)
        robot.led.on(ALL_LEDS, BLACK)
        wait(0.5, SECONDS)

def turning():
    robot.turn(RIGHT)

# Register multiple functions to the Event object
move_event(blink_leds)
move_event(turning)

move_event.broadcast()

# Move in a specified direction
move_event = Event()

def move_distance(movement_angle):
    robot.move_for(50, movement_angle)

# Change the parameter to modify how the robot moves
move_event(move_distance, (180,))
move_event.broadcast()

Broadcast

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

Usage:
event.broadcast()

parameter	description
event	先前创建的事件对象的名称。

# Blink LEDs while moving forward and turning
move_event = Event()

def blink_leds():
    while True:
        robot.led.on(ALL_LEDS, RED)
        wait(0.5, SECONDS)
        robot.led.on(ALL_LEDS, BLACK)
        wait(0.5, SECONDS)


move_event(blink_leds)

# Trigger the move_event Event
move_event.broadcast()
robot.move_at(0)

Broadcast and wait

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

Usage:
event.broadcast_and_wait()

parameter	description
event	先前创建的事件对象的名称。

# Move after the screen is pressed
move_event = Event()

def move_and_turn():
    robot.move_for(50, 0)
    robot.turn_for(RIGHT, 90)

move_event(move_and_turn)

while True:
    if robot.screen.pressing():
        move_event.broadcast_and_wait()
        break
robot.screen.print("Movement done.")