事件

初始化事件类

Event 构造函数创建一个 Event 对象。

此构造函数使用两个参数：

范围	描述
回调	可选。 先前定义的函数，当事件广播时将作为线程被调用。
arg	**可选。**用于向事件回调函数传递参数的元组。

# Define the function broadcasted_event().
def broadcasted_event():
    brain.screen.print("Event was broadcast")
# Construct an Event "event" with the
# Event class.
event = Event(broadcasted_event)

当引用 Event 类方法时，此“event”对象将在本 API 文档的所有后续示例中使用。

类方法

放（）

set(callback, arg) 方法为事件设置新的回调和参数。

参数	描述
打回来	事件触发时调用的新回调函数。
arg	**可选。**传递给回调函数的参数元组。

**返回：**无。

# Define a function event_occurred()
def event_occurred():
    brain.screen.set_cursor(1, 1)
    brain.screen.print("event occurred")

# Set the event to run event_occurred() instead of print()
# when the event is broadcast.
event = Event(event_occurred)
event.set(event_occurred)
# Broadcast event and run print().
event.broadcast()

播送（）

broadcast() 方法广播事件并导致所有已注册的回调函数运行。

**返回：**无。

def button_pressed():
    brain.play_sound(SoundType.ALARM)
    wait(0.5,SECONDS)

# Broadcast the event when the button is held down
# and turn when it is not.
event = Event(button_pressed)
event.set(button_pressed)
while True:
    if brain.buttonCheck.pressing():
        event.broadcast()
    else:
        drivetrain.turn(RIGHT)

广播并等待（）

broadcast_and_wait() 方法广播事件，导致所有已注册的回调函数运行，并等待所有回调函数完成。

**返回：**无。

def forward_and_turn():
    drivetrain.drive_for(FORWARD, 100, MM)
    drivetrain.turn_for(RIGHT, 90, DEGREES)

# Wait for a button to be pressed,then wait for
# the robot to be done moving and print a message.
event = Event(forward_and_turn)
event.set(forward_and_turn)
while not brain.buttonCheck.pressing():
    wait(0.1,SECONDS)
event.broadcast_and_wait()
brain.screen.print("Done!")