如何從另一個函數內調用函數？

Question

我正在創建一個簡單的GUI程序來管理優先級。我在從另一個函數中訪問函數時遇到麻煩。在我的程序中，我試圖創建一個GuiPart類的實例，然後調用g.addItem，但它似乎不能像那樣工作。我得到一個錯誤：

/usr/bin/python3.5 /home/cali/PycharmProjects/priorities/priorities.py 
Traceback (most recent call last): 
File "/home/cali/PycharmProjects/priorities/priorities.py", line 70, in > <module> 
    g.display() 
File "/home/cali/PycharmProjects/priorities/priorities.py", line 39, in > display 
    command = g.addItem) 
File "/usr/lib/python3.5/tkinter/__init__.py", line 2077, in grid_configure 
    + self._options(cnf, kw)) 
_tkinter.TclError: bad option "-command": must be -column, -columnspan, -in, > -ipadx, -ipady, -padx, -pady, -row, -rowspan, or -sticky 

這裏是我做了什麼：

# priorities.py 
# GUI program to manage priorities 

from tkinter import * 

class Priority: 

    def __init__(self, subject, priority): 
     self.subject = subject 
     self.priority = priority 

    def subject(self): 
     return self.subject 

    def priority(self): 
     return self.priority 


class GuiPart: 

    def __init__(self): 
     self.root = self.createWindow() 

    def createWindow(self): 

     root = Tk() 
     root.resizable(width = False, height = False) 
     root.title("Priorities") 

     return root 

    def createWidgets(self): 

     listBox = Listbox().grid(row=1) 

     buttonAdd = Button(text = "Add").grid(row = 2, 
            column = 0, 
            sticky = W, 
            command = g.addItem) 

     buttonRemove = Button(text="Remove").grid(row = 2, 
            column = 0, 
            sticky = W, 
            command = g.removeItem) 

     buttonEdit = Button(text="Edit").grid(row = 2, 
           column = 0, 
           sticky = E, 
           command = g.editItem) 

     textBox = Text().grid(row = 3) 

    def addItem(self, item): 
     item = Priority(item.subject, item.priority) 
     item.subject = g.textBox.get("1.0", 'end-1c') 

     g.listBox.insert(END, self) 

    def removeItem(self): 
     pass 

    def editItem(self): 
     pass 

class Client: 
    pass 

if __name__ == "__main__": 
    g = GuiPart() 
    g.createWidgets() 
    g.root.mainloop() 

Answer 1

讓我們來看看你的代碼的一部分...

buttonAdd = Button(text = "Add").grid(row = 2, 
           column = 0, 
           sticky = W, 
           command = g.addItem) 

這裏的主要問題是：command是對Button()參數構造函數，而不是.grid()方法。這就是你目前的錯誤來自哪裏。

第二個問題是您分配給buttonAdd的值是.grid()（始終爲None）的結果，而不是按鈕本身。如果你真的需要爲以後使用（通常，你不這樣做）的按鈕的引用，這必須被分成兩個語句：

buttonAdd = Button(text = "Add", command = g.addItem) 
    buttonAdd.grid(row = 2, 
        column = 0, 
        sticky = W) 

Answer 2

看到這個：

buttonAdd = Button(text = "Add").grid(row = 2, 
          column = 0, 
          sticky = W, 
          command = g.addItem) 
#         ^^^^^^^^^ 

buttonRemove = Button(text="Remove").grid(row = 2, 
          column = 0, 
          sticky = W, 
          command = g.removeItem) 
#         ^^^^^^^^^^^^ 

buttonEdit = Button(text="Edit").grid(row = 2, 
          column = 0, 
          sticky = E, 
          command = g.editItem) 
#         ^^^^^^^^^^ 

---

您是不調用函數你他們分配。 爲了調用它們，你必須傳遞參數給它們。

一個小例子解釋發生了什麼：

>>> id(print) 
1769760 
>>> some_var = print 
>>> id(some_var) 
1769760 
>>> some_var 
<built-in function print> 
>>> some_var('we assigned the built-in function "print" to the variable 
... some_var') 
we assigned the built-in function "print" to the variable some_var