Python 2.7乌龟onkey事件导致循环？

Question

from turtle import *
def PleaseStop():
 SomeWord = input("Which word?")
Screen().onkey(PleaseStop,"a")
Screen().listen()

Pressing "a" will make the program ask "Which word?" forever.

No way to stop it besides closing the program. How do I get onkey to call the function only once?

Answer 1

You need to remove the event bindings by calling onkey with None as first parameter :

import turtle

def OnKeyA():
    print 'Key "a" was pressed'
    turtle.Screen().onkey(None, 'a')

turtle.Screen().onkey(OnKeyA, 'a')
turtle.Screen().listen()
turtle.mainloop()

Answer 2

Doesn't solve the problem. Print is fine either way, input() is repeating itself forever, even with none.

I believe @Acorn was heading in the right direction with this but the example provided is incomplete. Here's what I feel is a more complete solution:

from turtle import Turtle, Screen, mainloop

def OnKeyA():
    screen.onkey(None, 'a')
    some_word = raw_input("Which word? ")
    turtle.write(some_word, font=('Arial', 18, 'normal'))

screen = Screen()
turtle = Turtle()

screen.onkey(OnKeyA, 'a')
print("Click on turtle window to make it active, then type 'a'")

screen.listen()
mainloop()

Note that this approach is awkward, clicking the turtle graphics window to make it active, hitting 'a', going back to the console window to type your word. If/when you move to Python 3, you can use the turtle function textinput() to prompt for text from the user without having to use input() from the console.