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[英]Closing current window when opening a new window in tkinter python
[英]Error message when opening new window in Tkinter
我是 Tkinter 的初學者,我試圖了解如何打開一個新窗口來計算一些變量。
在這個例子中,出現了一個帶有按鈕的第一個窗口(“輸入”)。 按“開始”后,將創建一個新窗口,我可以在其中導入周長值以按“轉換”按鈕轉換為直徑。
當我按下這個按鈕時,控制台中會出現一個錯誤:
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Python27\lib\lib-tk\Tkinter.py", line 1470, in __call__
return self.func(*args)
File "C:/Users/samsung/PycharmProjects/test_FirstDensity/openANDread.py", line 55, in convert
convert = tk.Button(c2d, text="Convert", command=convert_c2d, activeforeground="red")
UnboundLocalError: local variable 'convert_c2d' referenced before assignment
我嘗試了幾種解決方案但沒有解決我的問題。
我的代碼是:
from __future__ import division
from Tkinter import *
from math import pi
import tkMessageBox
import Tkinter, Tkconstants, tkFileDialog
from numpy import nan
import Tkinter as tk
class MainWindow(Frame):
def __init__(self):
Frame.__init__(self)
self.filename = None
self.master.title("input")
self.master.minsize(250, 150)
self.grid(sticky=E+W+N+S)
top=self.winfo_toplevel()
top.rowconfigure(0, weight=1)
top.columnconfigure(0, weight=1)
for i in range(1): self.rowconfigure(i, weight=1)
self.columnconfigure(1, weight=1)
self.button0 = Button(self, text="start", command=self.convert, activeforeground="red")
self.button0.grid(row=0, column=1, pady=2, padx=2, sticky=E+W+N+S)
def convert(self):
c2d = Tk()
c2d.title("C2DBH converter")
c2d.minsize(350, 150)
c2d.grid()
res = StringVar(c2d)
res.set("---")
for i in range(3): c2d.rowconfigure(i, weight=1)
c2d.columnconfigure(1, weight=1)
label_c = tk.Label(c2d, text='Circumference')
label_c.grid(row=0, column=0, padx=2, sticky=E+W+N+S)
entry_c = Entry(c2d)
entry_c.grid(row=0, column=1, padx=2,sticky=E+W+N+S)
label_d = tk.Label(c2d, text='Diameter')
label_d.grid(row=1, column=0, padx=2, sticky=E+W+N+S)
result = tk.Label(c2d, textvariable=res, fg="red")
result.grid(row=1, column=1, pady=2, padx=2, sticky=E+W+N+S)
convert = tk.Button(c2d, text="Convert", command=convert_c2d, activeforeground="red")
convert.grid(row=2, column=0, columnspan=2, pady=2, padx=2, sticky=E+W+N+S)
def convert_c2d(n):
if not n.get():
return res.set("Insert a numeric value.")
try:
c = float(n.get())
diameter = c/pi
return res.set(str(diameter))
except ValueError:
return res.set("Insert a numeric value.")
您應該在引用函數之前定義它。
>>> def f():
... convert_c2d(1)
... def convert_c2d(n):
... pass
...
>>> f()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 2, in f
UnboundLocalError: local variable 'convert_c2d' referenced before assignment
>>> def g():
... def convert_c2d(n):
... pass
... convert_c2d(1)
...
>>> g()
>>>
只需更改以下代碼即可解決您的問題:
def convert_c2d(n):
if not n.get():
return res.set("Insert a numeric value.")
try:
c = float(n.get())
diameter = c/pi
return res.set(str(diameter))
except ValueError:
return res.set("Insert a numeric value.")
convert = tk.Button(c2d, text="Convert", command=convert_c2d, activeforeground="red")
convert.grid(row=2, column=0, columnspan=2, pady=2, padx=2, sticky=E+W+N+S)
更新
convert_c2d
接受一個參數。 但是 tkinter 不會使用參數調用命令回調。 您應該使用另一個函數(或 lambda 如下)傳遞它:
convert = tk.Button(c2d, text="Convert", command=lambda: convert_c2d(entry_c),
activeforeground="red")
或者您可以更改convert_c2d
不接受任何參數,並使函數直接訪問entry_c
。 (嵌套函數可以從封閉范圍訪問變量)。
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