更改Tkinter中的按钮状态

Question

我正在处理的程序允许用户输入文本并检查它是否是回文。输入顺序为order（），用testPalindrome（orderedText）进行测试，然后使用showResult（Palindrome）显示结果。当谈到保存回文时，我的问题就出现了。如果用户被验证为回文，用户应该能够保存输入。我认为这是有道理的，如果保存按钮被禁用，直到一个输入已被测试为真。所以我在showResult（Palindrome）中放置了“saveButton.config（state ='normal'）”，但这不起作用。该错误说“全局名称”saveButton'未定义“，我可以明白为什么。但是，我无法做到正确。我想知道是否有可能通过对这一行文本的补充来解决这个问题，或者如果我必须做出更彻底的修改。 （我试过例如把“saveButton”到一个全局变量，如“inputEntry”，但不管是什么原因，我不能得到这工作的。）

import Tkinter 

    root = Tkinter.Tk() 
    infoLabel = Tkinter.Label(root, text = 'Enter a text and check if it is a palindrome.', height = 12, width = 64, bg = 'green') 
    inputEntry = Tkinter.Entry(root, width = 64) 

    def main(): 
     window() 
     Tkinter.mainloop() 

    def window(): 
     root.title('Palindrome detector') 
     root.geometry('534x285+500+250') 
     infoLabel.grid(row = 0, rowspan = 1, column = 0, columnspan = 4, pady = 8, padx = 8) 
     inputEntry.insert(0, 'Enter text...') 
     inputEntry.grid(row = 1, rowspan = 1, column = 0, columnspan = 4, padx = 4) 
     verifyButton = Tkinter.Button(root, text = 'Verify', width = 7, command = order).grid(row = 2, column = 0, pady = 10) 
     saveButton = Tkinter.Button(root, text = 'Save', state = 'disabled', width = 7, command = save).grid(row = 2, column = 3) 

    def order(): 
     Text_input = inputEntry.get() 
     orderedText = Text_input.replace(" ", "") 
     orderedText = orderedText.lower() 
     orderedText = filter(str.isalnum, orderedText) 
     if any(char.isalpha() or char.isdigit() for char in orderedText): 
      testPalindrome(orderedText) 
     else: 
      infoLabel.config(text = 'The input must contain at least one alphanumeric character.', bg = 'red') 

    def testPalindrome(orderedText): 
     Palindrome = True 
     i = 0 
     for char in orderedText: 
      if orderedText[i] == orderedText[-(i+1)]: 
       Palindrome = True 
       i += 1 
      else: 
       Palindrome = False 
       break 
     showResult(Palindrome) 

    def showResult(Palindrome): 
     if Palindrome == True: 
      infoLabel.config(text = 'Yes! "' + str(inputEntry.get()) + '" is a palindrome!', bg = 'green') 
      saveButton.config(state = 'normal') 
     else: 
      infoLabel.config(text = 'No! "' + str(inputEntry.get()) + '" is not a palindrome!', bg = 'red') 
      saveButton.config(state = 'disabled') 

    def save(): 
     savePalindrome = inputEntry.get() 
     palindromes_file = open("Palindromes.txt", "a") 
     palindromes_file.write(savePalindrome + "\n") 
     palindromes_file.close() 
     infoLabel.config(text = '"' + str(savePalindrome) + '" has been saved to file.', bg = 'green') 
     saveButton.config(state = 'disabled') 

    if __name__ == '__main__': 
     main() 

编辑：阅读的答案后，我跟着教科书，并试图用班级来重写整个事物。当然，可能会有任何数量的缺陷。我现在关心的是“NameError：全球名称'testPalindrome'未定义”。错误（第7行）顺序（自我）。我看不出为什么这条线和order（self）和testPalindrome（self）之间的“桥梁”突然出现问题？

import Tkinter 
    import tkMessageBox 

    root = Tkinter.Tk() 

    class MyGUI: 
     def __init__(self, master): 
      self.master = master 
      master.title('Palindrome detector') 
      master.geometry('534x285+500+250') 
      self.infoLabel = Tkinter.Label(self.master, text = 'Enter a text and check if it is a palindrome.', height = 12, width = 64, bg = 'green') 
      self.inputEntry = Tkinter.Entry(self.master, width = 64) 
      self.infoLabel.grid(row = 0, rowspan = 1, column = 0, columnspan = 4, pady = 8, padx = 8) 
      self.inputEntry.insert(0, 'Enter text...') 
      self.inputEntry.grid(row = 1, rowspan = 1, column = 0, columnspan = 4, padx = 4) 
      self.verifyButton = Tkinter.Button(self.master, text = 'Verify', width = 7, command = self.order) 
      self.verifyButton.grid(row = 2, column = 0, pady = 10) 
      self.saveButton = Tkinter.Button(self.master, text = 'Save', state = 'disabled', width = 7, command = self.save) 
      self.saveButton.grid(row = 2, column = 3) 

     def order(self): 
      self.Text_input = self.inputEntry.get() 
      self.orderedText = self.Text_input.replace(" ", "") 
      self.orderedText = self.orderedText.lower() 
      self.orderedText = filter(str.isalnum, self.orderedText) 
      if any(char.isalpha() or char.isdigit() for char in self.orderedText): 
       testPalindrome(self) 
      else: 
       self.infoLabel.config(text = 'The input must contain at least one alphanumeric character.', bg = 'red') 

     def testPalindrome(self): 
      self.Palindrome = True 
      i = 0 
      for char in self.orderedText: 
       if self.orderedText[i] == self.orderedText[-(i+1)]: 
        self.Palindrome = True 
        i += 1 
       else: 
        self.Palindrome = False 
        break 
      showResult(self) 

     def showResult(self): 
      if self.Palindrome == True: 
       self.infoLabel.config(text = 'Yes! "' + str(self.inputEntry.get()) + '" is a palindrome!', bg = 'green') 
       self.saveButton.config(state = 'normal') 
      else: 
       self.infoLabel.config(text = 'No! "' + str(self.inputEntry.get()) + '" is not a palindrome!', bg = 'red') 
       self.saveButton.config(state = 'disabled') 

     def save(self): 
      self.savePalindrome = self.inputEntry.get() 
      self.palindromes_file = open("Palindromes.txt", "a") 
      self.palindromes_file.write(self.savePalindrome + "\n") 
      self.palindromes_file.close() 
      self.infoLabel.config(text = '"' + str(self.savePalindrome) + '" has been saved to file.', bg = 'green') 
      self.saveButton.config(state = 'disabled') 

    my_gui = MyGUI(root) 
    Tkinter.mainloop() 

Answer 1

您在功能创建saveButton所以它是局部变量，它不是在其他功能avaliable。您可以使用global saveButton中的window()使此变量全局。

def window(): 
    global saveButton 

    # .... 

    saveButton = Tkinter.Button(...) 
    saveButton.grid(...) 

-

正如凯文已经说过：

此行

saveButton = Tkinter.Button(...).grid(...) 

分配None到saveButton因为grid()总是返回None

使用

saveButton = Tkinter.Button(...) 
saveButton.grid(...) 

或

Tkinter.Button(...).grid(...) 

如果你不需要saveButton变量。

Answer 2

只需在您的验证功能中打电话，因为您想每次都是自动保存时，它是一个回文。您可以将该值传递给该函数，而不是第二次获取该值。

def testPalindrome(orderedText): 
    ## change to False so an empty string will not 
    ## register as True 
    Palindrome = False 
    i = 0 
    for char in orderedText: 
     if orderedText[i] == orderedText[-(i+1)]: 
      Palindrome = True 
      i += 1 
     else: 
      Palindrome = False 
      break 
    showResult(Palindrome) 
    if Palindrome: 
     save(orderedText) 

下一步学习类，因为它解决了这些问题。网络上的许多教程之一http://python-textbok.readthedocs.org/en/latest/Introduction_to_GUI_Programming.html要使按钮成为全局，请将其放入全局名称空间（如inputEntry）。

root = Tkinter.Tk() 
infoLabel = Tkinter.Label(root, text = 'Enter a text and check if it is a palindrome.', height = 12, width = 64, bg = 'green') 
inputEntry = Tkinter.Entry(root, width = 64) 

saveButton = Tkinter.Button(root, text = 'Save', state = 'disabled', width = 7, command = save) 
saveButton.grid(row = 2, column = 3)