Python:tkinter属性

Question

我正在做一个课堂作业，我一直收到一个AttributeError。这是我的代码：

from tkinter import *

class Lab12():
    def __init__(self, master):
        self.frm = Frame(master)
        self.frm.grid()
        self.buttons()
        self.basevalue = IntVar()
        self.expvalue = IntVar()
        self.strvalue = StringVar()

    def buttons(self):
        self.base = Scale (self.frm)
         self.base['orient'] = 'horizontal'
        self.base['length'] = 10
        self.base['from'] = 1
        self.base['to'] = 10
        self.base['variable'] = self.basevalue

        self.exp = Scale (self.frm)
        self.exp['orient'] = 'horizontal'
        self.exp['length'] = 25
        self.exp['from'] = 1
        self.exp['to'] = 25
        self.exp['variable'] = self.expvalue

        self.lbl = Label (self.frm)
        self.lbl['textvariable'] = self.strvalue

        self.result = Button (self.frm)
        self.result['text'] = "Click to get result"
        self.result['command'] = self.do_res

        self.base.grid(row = 0, column = 0)
        self.exp.grid(row = 1, column = 0)
        self.lbl.grid(row = 2, column = 1)
        self.result.grid(row = 2, column = 1)

    def do_res(self):
        x = self.basevalue.get()
        y = self.expvalue.get()
        self.strvalue.set(str(x) + ' raised to ' + str(y) + ' is ' + str(x     ** y))

def py_lab():
    lab = Tk()
    lab.title("lab12")
    lab.geometry("400x400")
    labclass = Lab12(lab)
    lab.mainloop()
py_lab()

错误是：

^{pr2}$

如果我把

self.base['variable'] = self.basevalue

我还是有错误自我价值观以及自身值还有台词。我不太确定是什么导致了这个问题，所以任何建议都有帮助。在

Answer 1

只有在调用^{之后，才初始化这些属性。颠倒__init__方法中的顺序，然后它将工作：

def __init__(self, master):
    self.frm = Frame(master)
    self.frm.grid()
    self.basevalue = IntVar()
    self.expvalue = IntVar()
    self.strvalue = StringVar()
    self.buttons() # call buttons after initializing above attributes

Answer 2

您应该在__init__方法中的属性声明之后调用方法buttons。在

    ...
    self.basevalue = IntVar()
    self.expvalue = IntVar()
    self.strvalue = StringVar()

    self.buttons()
    ...