event.getKeys only works when a window is open

Coding
2

I have found that the ioHub getPresses() command works in the absence of a window and this is a good alternative to event.getKeys(). I initially struggled to understand how to clear the keyboard buffer prior to the getPresses() statement, because clearEvents() did not work; but then I discovered that clearEvents(device_label=‘keyboard’) does the trick. (In the code below, the first getPresses() command has clear=False so that it leaves a keypress event in the buffer for clearEvents to clear up.)

from psychopy.iohub import launchHubServer

io=launchHubServer()
keyboard = io.devices.keyboard

print "START"
while True:
    if keyboard.getPresses(clear=False):
        print "event"
        break

io.clearEvents(device_label='keyboard')

print "MIDDLE"
while True:
    if keyboard.getPresses():
        print "event"
        break
        
print "END"
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