python - 再次点击按钮时出错

Question

这个问题已经有答案了:

Why does code like `str = str(...)` cause a TypeError, but only the second time? (20 个回答)

已关闭 10 个月前。

我正在尝试制作一个 G.U.I.应用程序会将每个条目的输入乘以特定值，然后将标签的文本设置为总计。

这是我当前的代码:

import Tkinter as tk

# Classes
class Application(tk.Frame):
    def __init__(self):

        # Create G.U.I. Framework
        self.root = tk.Tk()
        tk.Frame.__init__(self)
        self.root.title("Job Estimator")
        self.root.geometry("280x200")

        # Create G.U.I. Widgets
        tk.Label(self.root, text="Labour:    "  + unichr(163) + "40.00 x Hours")  .grid(row=0, column=0, sticky=tk.W)
        tk.Label(self.root, text="Travel:     " + unichr(163) + "1.00   x Miles") .grid(row=1, column=0, sticky=tk.W)
        tk.Label(self.root, text="Plastic:    " + unichr(163) + "2.00   x Metres").grid(row=2, column=0, sticky=tk.W)
        tk.Label(self.root, text="Copper:  "    + unichr(163) + "3.00   x Metres").grid(row=3, column=0, sticky=tk.W)
        tk.Label(self.root, text="Chrome: "     + unichr(163) + "4.00  x Metres") .grid(row=4, column=0, sticky=tk.W)
        tk.Label(self.root, text="Total: "      + unichr(163))                    .grid(row=5, column=0, sticky=tk.W)

        self.totalLabel = tk.Label(self.root, text="0.00")
        self.totalLabel.grid(row=5, column=1, sticky=tk.W)

        self.LabourInput = tk.Entry(self.root)
        self.LabourInput.grid(row=0, column=1, sticky=tk.S)

        self.TravelInput = tk.Entry(self.root)
        self.TravelInput.grid(row=1, column=1, sticky=tk.S)

        self.PlasticInput = tk.Entry(self.root)
        self.PlasticInput.grid(row=2, column=1, sticky=tk.S)

        self.CopperInput = tk.Entry(self.root)        
        self.CopperInput.grid(row=3, column=1, sticky=tk.S)

        self.ChromeInput = tk.Entry(self.root)        
        self.ChromeInput.grid(row=4, column=1, sticky=tk.S)     

        CalculateButton = tk.Button(self.root, text="Calculate", command=lambda: calc.GrandTotal()).grid(row=6, column=0, sticky=tk.W)

class Calculator():
    def __init__(self):
        pass

    def Multiply(self, number, rate):

        NumFloat = float(number)
        RateFloat = float(rate)
        return NumFloat * RateFloat

    def GrandTotal(self): # Adds each entry field to produce and return a grand total. 

        # Set Variables

        self.LabourTotal  = self.Multiply(app.LabourInput.get(), 40)
        self.TravelTotal  = self.Multiply(app.TravelInput.get(), 1)
        self.PlasticTotal = self.Multiply(app.PlasticInput.get(), 2)
        self.CopperTotal  = self.Multiply(app.CopperInput.get(), 3)
        self.ChromeTotal  = self.Multiply(app.ChromeInput.get(), 4)

        self.GrandTotal   = self.LabourTotal + self.TravelTotal + self.PlasticTotal + self.CopperTotal + self.ChromeTotal

        return app.totalLabel.config(text=self.GrandTotal) # Return the total value.

calc = Calculator()
app = Application()
app.mainloop()

这很好，除了当我单击计算按钮并且它起作用时，如果我再次单击它，我会收到一条错误消息:

>>> 
Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Python27\lib\lib-tk\Tkinter.py", line 1410, in __call__
    return self.func(*args)
  File "C:\Users\Stephen\Desktop\test.py", line 39, in <lambda>
    CalculateButton = tk.Button(self.root, text="Calculate", command=lambda: calc.GrandTotal()).grid(row=6, column=0, sticky=tk.W)
TypeError: 'float' object is not callable

Answer 1

您正在将 Calculator 类的 self.GrandTotal 属性更改为 GrandTotal 函数内的 float ，行 -

self.GrandTotal   = self.LabourTotal + self.TravelTotal + self.PlasticTotal + self.CopperTotal + self.ChromeTotal

因此，执行此行后，方法 GrandTotal 会被 float 覆盖，因此当您尝试再次单击该按钮时，它会尝试调用 calc.GrandTotal() 但 GrandTotal 现在是一个 float ，因此会出错。

您应该为 float 使用不同的名称。示例-

self.complete_total = self.LabourTotal + self.TravelTotal + self.PlasticTotal + self.CopperTotal + self.ChromeTotal

return app.totalLabel.config(text=self.complete_total) # Return the total value.