beeware制作聊天软件的空指针问题

Question

报错

RuntimeError: cannot call null pointer pointer from cdata 'int(*)(void *, int)'

"""
My first application
"""
import toga
from toga.style import Pack
from toga.style.pack import COLUMN, ROW
import httpx
import socket
import threading
import json

IP = '8c3i911557.zicp.fun'
PORT = '30479'
user = ''
listbox1 = ''  # 用于显示在线用户的列表框
show = 1  # 用于判断是开还是关闭列表框
users = []  # 在线用户列表
chat = '------Group chat-------'  # 聊天对象

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((IP, int(PORT)))
if user:
    s.send(user.encode())  # 发送用户名
else:
    s.send('用户名不存在，'.encode())
    user = '手机用户'

class chat(toga.App):
    def startup(self):
        name = self.name_input.value
        main_box = toga.Box(style=Pack(direction=COLUMN))

        name_label = toga.Label(
            "输入：",
            style=Pack(padding=(0, 5))
        )
        self.name_input = toga.TextInput(style=Pack(flex=1))

        name_box = toga.Box(style=Pack(direction=ROW, padding=5))
        name_box.add(name_label)
        name_box.add(self.name_input)

        button = toga.Button(
            "发送",
            on_press=self.say_hello,
            style=Pack(padding=5)
        )

        main_box.add(name_box)
        main_box.add(button)

        self.main_window = toga.MainWindow(title=self.formal_name)
        self.main_window.content = main_box
        self.main_window.show()

    def say_hello(self, widget):
        print(f"Hello, "+str(name))
        def send(*args):
            message = str(name) + '~' + user + '~' + chat
            s.send(message.encode())
            INPUT.set('')

def main():
    return chat()

Answer 1

解决问题后我用v给5元