TypeError:*支持的操作数类型*:'type'和'float'

Question

我正在尝试自学python并遇到了一个我不确定的错误.错误看起来像这样:

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python3.2/tkinter/__init__.py", line 1426, in __call__
    return self.func(*args)
  File "/home/pi/python/SolutionMixerGUI.py", line 39, in calculate
    fgTotal = self.vol * fgML
TypeError: unsupported operand type(s) for *: 'type' and 'float'

我知道这个错误告诉我,我不能将这两种类型相乘,我很困惑'类型'是什么.任何人都可以帮我清除这个错误.完整代码如下.

from tkinter import *

class App:
    def __init__(self,master):
        frame = Frame(master)
        frame.pack()
        Label(frame, text='Solution in liters:').grid(row=0, column=0)
        self.vol = DoubleVar
        Entry(frame, textvariable=self.vol).grid(row=0, column=1)
        Label(frame, text='Growth Stage (1-5):').grid(row=1, column=0)
        self.stage = IntVar
        Entry(frame, textvariable=self.stage).grid(row=1, column=1)
        self.fgTotal = DoubleVar
        self.fmTotal = DoubleVar
        self.fbTotal = DoubleVar
        Label(frame, textvariable=self.fgTotal).grid(row=2, column=0)
        Label(frame, textvariable=self.fmTotal).grid(row=2, column=2)
        Label(frame, textvariable=self.fbTotal).grid(row=2, column=3)
        button = Button(frame, text='Calculate', command=self.calculate)
        button.grid(row=3, column=1, sticky=(W, E))

    def calculate(self):
        if self.stage == 1:
             #Seedlings
            fgML,fmML,fbML = 0.33,0.33,0.33
        elif self.stage == 2:
            #Mild Veg
            fgML,fmML,fbML = 1.32,1.32,1.32
        elif self.stage == 3:
            #Aggresive Veg
            fgML,fmML,fbML = 3.96,2.64,1.32
        elif self.stage == 4:
            #Tranistion to Bloom
            fgML,fmML,fbML = 2.64,2.64,2.64
        else:
            #Blooming and Ripening
            fgML,fmML,fbML = 1.32,2.64,3.96
        fgTotal = self.vol * fgML
        fmTotal = self.vol * fmML
        fbTotal = self.vol * fbML


root = Tk()
root.wm_title('Solution Mixer')
app = App(root)
root.mainloop()

Answer 1

你忘了给构造函数打电话了.

    self.vol = DoubleVar()