python - 使用turtle.onclick() 改变变量

Question

每次单击海龟时，我如何将变量clicks增加 1：

import turtle
jeff = turtle.Turtle()
jeff.shape("turtle")
jeff.color("blue")
clicks=0


def left(x,y): 
    jeff.left(90) 
    clicks=clicks+1
    print "you have"+clicks+"clicks."


jeff.onclick(left)

当我输入这个时，clicks=clicks+1它给了我：

UnboundLocalError：分配前引用的局部变量“点击”

标签： pythonpython-2.7turtle-graphics

Answer 1

变量clicks是全局的。任何想要修改全局变量的函数都必须声明该变量global：

from turtle import Turtle, mainloop

clicks = 0

def left(x, y):
    global clicks

    jeff.left(90)
    clicks += 1
    print "you have " + str(clicks) + " clicks."

jeff = Turtle()
jeff.shape("turtle")
jeff.color("blue")

jeff.onclick(left)

mainloop()