IntVar（）。trace（）不起作用

Question

我剛開始在Python/Tkinter中編寫一個小Pymol插件。在這裏，我試圖設置一個切換按鈕，並在點擊時報告它的狀態。按鈕上下移動，但toggleAVA永遠不會被調用。任何想法爲什麼？

from Tkinter import * 
import tkMessageBox 

class AVAGnome: 

    def __init__(self, master): 
     # create frames 
     self.F1 = Frame(rootGnome, padx=5, pady=5, bg='red') 

     # checkbuttons 
     self.AVAselected = IntVar() 
     self.AVAselected.trace("w", self.toggleAVA) 
     self.AVAbutton = Checkbutton(self.F1, text='AVA', indicatoron=0, variable=self.AVAselected) 

     # start layout procedure 
     self.layout() 

    def layout(self): 
     self.F1.pack(side=TOP, fill=BOTH, anchor=NW) 

     #entry and buttons 
     self.AVAbutton.pack(side=LEFT) 

    def toggleAVA(self, *args): 
     if (self.AVAselected.get()): 
      avastatus = "selected" 
     else: 
      avastatus = "unselected" 
     tkMessageBox.showinfo("AVA status", avastatus) 

def __init__(self): 
    open_GnomeUI() 

def open_GnomeUI(): 
    # initialize window 
    global rootGnome 
    rootGnome = Tk() 
    rootGnome.title('AVAGnome') 
    global gnomeUI 
    gnomeUI = AVAGnome(rootGnome) 

Answer 1

我用Pymol測試了你的代碼。

問題是因爲您使用Tk()來創建您的窗口。您必須使用Toplevel()，然後才能正確使用trace()或command=。

---

Pymol與tkinter創建了只能有一個與Tk()創建的窗口 - 它是在程序主窗口。其他窗口必須使用Toplevel()創建。

Answer 2

我已在下面附上您的代碼的工作版本。你可以參考它來了解你出錯的地方。通常，如果您使用的是類格式，則必須考慮如何構造代碼。這將幫助您更好地形象化代碼並進行調試。你可以閱讀這個discussion來幫助你。

from Tkinter import * 
import tkMessageBox 

class AVAGnome(Frame): 

    def __init__(self, parent): 
     Frame.__init__(self, parent) 

     # create frames 
     self.F1 = Frame(self, padx=5, pady=5, bg='red') 

     # checkbutton 
     self.AVAselected = IntVar() 
     self.AVAselected.trace("w", self.toggleAVA) 
     self.AVAbutton = Checkbutton(
      self.F1, text='AVA', indicatoron=0, width=10, 
      variable=self.AVAselected) 

     # start layout procedure 
     self.F1.pack(side=TOP, fill=BOTH, anchor=NW) 
     self.AVAbutton.pack(side=LEFT) #entry and buttons 

    def toggleAVA(self, *args): 
     if (self.AVAselected.get()): 
      avastatus = "selected" 
     else: 
      avastatus = "unselected" 
     tkMessageBox.showinfo("AVA status", avastatus) 

if __name__ == '__main__': 
    rootGnome = Tk() 
    rootGnome.title('AVAGnome') 
    gnomeUI = AVAGnome(rootGnome) 
    gnomeUI.pack(fill="both", expand=True) 
    gnomeUI.mainloop() 

更新：上面的代碼結構是獨立的Tkinter程序。我試圖將此工作代碼轉換爲遵循Pymol插件示例。修訂後的代碼張貼在下面，易於進一步修訂。

# https://pymolwiki.org/index.php/Plugins_Tutorial 
# I adapted from the example in the above link and converted my previous code to 
# 
from Tkinter import * 
import tkMessageBox 

def __init__(self): # The example had a self term here. 
    self.open_GnomeUI() 


class AVAGnome(Frame): 
    def __init__(self, parent): 
     Frame.__init__(self, parent) 

     # create frames 
     self.F1 = Frame(self, padx=5, pady=5, bg='red') 

     # checkbutton 
     self.AVAselected = IntVar() 
     self.AVAselected.trace("w", self.toggleAVA) 
     self.AVAbutton = Checkbutton(
      self.F1, text='AVA', indicatoron=0, width=10, 
      variable=self.AVAselected) 

     # start layout procedure 
     self.F1.pack(side=TOP, fill=BOTH, anchor=NW) 
     self.AVAbutton.pack(side=LEFT) #entry and buttons 

    def toggleAVA(self, *args): 
     if (self.AVAselected.get()): 
      avastatus = "selected" 
     else: 
      avastatus = "unselected" 
     tkMessageBox.showinfo("AVA status", avastatus) 

# Note, I added a "self" term throughout function. 
# Try w/ & w/o "self" to see which works. 
def open_GnomeUI(self): 
    self.rootGnome = Tk() 
    self.rootGnome.title('AVAGnome') 
    self.gnomeUI = AVAGnome(self.rootGnome) 
    self.gnomeUI.pack(fill="both", expand=True) 
    self.gnomeUI.mainloop()