Python 对象实例缺少属性？

Question

我正在尝试使用 TKinker，但也在尝试理解面向对象的编程。我不断收到同样的错误，

File "C:/Users/User/Documents/Python Scripts/tK_Slider.py", line 28, in getAngle print self.scale1.get() AttributeError: App instance has no attribute 'scale1'

我的代码，

from Tkinter import *

class App:

    def __init__(self, master):

        frame = Frame(master)
        frame.pack()

        self.scale1 = Scale(master, from_=0, to=180, command=self.getAngle(1))
        self.scale1.pack(side=LEFT)
        self.scale2 = Scale(master, from_=0, to=180, command=self.getAngle(2))
        self.scale2.pack(side=LEFT)
        self.scale3 = Scale(master, from_=0, to=180, command=self.getAngle(3))
        self.scale3.pack(side=LEFT)
        self.scale4 = Scale(master, from_=0, to=180, command=self.getAngle(4))
        self.scale4.pack(side=LEFT)

    def getAngle(self, slider):
        if slider==1:
            print self.scale1.get()
        if slider==2:
            print self.scale2.get()            
        if slider==3:
            print self.scale3.get()
        if slider==4:
            print self.scale4.get()

root = Tk()
app = App(root)
root.mainloop()

我误会了什么？

我想在我试图查询它的值之前我已经创建了属性 scale1，那么为什么它没有转移到 getAngle()?

Answer 1

这会立即调用 self.getAngle，此时 self.scale1 尚未设置。

self.scale1 = Scale(master, from_=0, to=180, command=self.getAngle(1))

您需要使用 lambda 函数进行间接寻址：

self.scale1 = Scale(master, from_=0, to=180, command=lambda ev: self.getAngle(1))

Python 对象实例缺少属性？

Python object instance missing attribute?

python

attributes

tkinter