找不到 Turtle 命令名称

Question

我在调用函数时遇到问题。这是一个示例调用：

def polyline(t,n,length,angle):
    """Draws n line segments with the given length and 
    angle(in degrees) between them. t is a turtle.
    """
    for i in range(n):
        t.fd(length)
        t.lt(angle)

关联的调用是这样的

alex=turtle.Turtle()

polyline(alex,5,100,90)

我已经导入了 turtle，但出现以下错误：

TclError: invalid command name ".!canvas"

我错过了什么？

Answer 1

看来我必须在调用函数之前不断地定义alex。例如这有效：

 def polyline(t,n,length,angle):
    """Draws n line segments with the given length and 
    angle(in degrees) between them. t is a turtle.
    """
    for i in range(n):
        t.fd(length)
        t.lt(angle)


alex=turtle.Turtle() 
#Test polyline
polyline(alex,5,780,90)

这失败了：

alex=turtle.Turtle() 
#insert some other functions


 #define polyline function

#call polyline

找不到 Turtle 命令名称

Turtle command name not found

python

turtle-graphics