用作类对象时的 tkinter 列表框错误

Question

I want to create a class of Listbox object so that it can be used anywhere it is needed but it throws TypeError error, here is my code:

import tkinter as tk

class cls_list(tk.Listbox):
    def __init__(self, master, callfrom):
        tk.Listbox.__init__(self, master, callfrom)

        callfrom.bind("<KeyRelease>", self.show_list)

    def show_list(self, event):
        x = callfrom.winfo_x()
        y = callfrom.winfo_y()
        h = callfrom.winfo_height()
        self.place(x = x, y = y+h)
        self.insert('end',*('Banana','Orange','Apple','Mango'))

if __name__ == '__main__':
    root = tk.Tk()
    ent = tk.Entry(root, font = (None, 20))
    lst = cls_list(root, ent)
    ent.pack()
    root.mainloop()

Can someone correct me what I am doing wrong? Here is complete Exception occurred:

  File "/home/waheed/env_pinpoint/lib/python3.9/site-packages/test_listbox.py", line 5, in __init__
    tk.Listbox.__init__(self, master, callfrom)
  File "/usr/lib/python3.9/tkinter/__init__.py", line 3162, in __init__
    Widget.__init__(self, master, 'listbox', cnf, kw)
  File "/usr/lib/python3.9/tkinter/__init__.py", line 2566, in __init__
    BaseWidget._setup(self, master, cnf)
  File "/usr/lib/python3.9/tkinter/__init__.py", line 2537, in _setup
    if 'name' in cnf:
  File "/usr/lib/python3.9/tkinter/__init__.py", line 1652, in cget
    return self.tk.call(self._w, 'cget', '-' + key)
TypeError: can only concatenate str (not "int") to str

This is what I have achieved so far.

import tkinter as tk

if __name__ == '__main__':
    root = tk.Tk()
    root.geometry('400x400')
    ent = tk.Entry(root, font = (None, 20))
    lst = tk.Listbox(root, font = (None, 20))
    ent.pack()
    ent.focus_set()

    def hide_list(event):
        index = int(lst.curselection()[0])
        val = lst.get(index)
        ent.delete(0,'end')
        ent.insert(0,val)
        lst.place_forget()

    def show_list(event):
        ent.update_idletasks()
        x = ent.winfo_x()
        y = ent.winfo_y()
        h = ent.winfo_height()
        lst.place(x = x, y = y+h)
        items = ['Banana','Orange','Apple','Mango']
        searchkey = ent.get()
        lst.delete(0, "end")
        for item in items:
            if searchkey.lower() in item.lower():
                lst.insert("end", item)
        n = lst.size()
        if n < 15:
            lst.config(height = 0)
        else:
            lst.config(height = 15)

    ent.bind("<KeyRelease>", show_list)
    lst.bind("<<ListboxSelect>>", hide_list)
    root.mainloop()

And now I want to make it an object (separate class) for using in multiple scripts.

I hope now I have explained my question properly.

Answer 1

I'm not sure exactly what you're trying to do, so the following probably doesn't "work", but the changes shown will get rid of the TypeError which was because of passing the wrong number of arguments to the base class __init__() method.

import tkinter as tk


class ClsList(tk.Listbox):
    def __init__(self, master, callfrom):
        tk.Listbox.__init__(self, master)  # Initialize base class.
        self.callfrom = callfrom  # Save for use in other methods.
        self.callfrom.bind("<KeyRelease>", self.show_list)

    def show_list(self, event):
        x = self.callfrom.winfo_x()       # Refer to attribute self.callfrom.
        y = self.callfrom.winfo_y()       # Refer to attribute self.callfrom.
        h = self.callfrom.winfo_height()  # Refer to attribute self.callfrom.
        self.place(x=x, y=y+h)
        self.insert('end', *('Banana','Orange','Apple','Mango'))


if __name__ == '__main__':
    root = tk.Tk()
    ent = tk.Entry(root, font=(None, 20))
    lst = ClsList(root, ent)
    ent.pack()
    lst.pack()  # Added.
    root.mainloop()

I also made a few other cosmetic changes to make the code conform more the the PEP 8 - Style Guide for Python Code guidelines.

Answer 2

The specific error you're asking about is caused because you're passing callfrom here: tk.Listbox.__init__(self, master, callfrom) .

The listbox widget doesn't know what to do with callfrom , it expects the second positional argument to be a dictionary.

The proper way to initialize the class is without callfrom . You will need to save callfrom as an instance attribute if you need to use it outside of the __init__ .

def __init__(self, master, callfrom):
    tk.Listbox.__init__(self, master)
    self.callfrom = callfrom
    ...


def show_list(self, event):
    x = self.callfrom.winfo_x()
    y = self.callfrom.winfo_y()
    h = self.callfrom.winfo_height()
    ...