'NoneType' object has no attribute 'delegate' exception when connecting

• bleak version: 0.8.0
• Python version: Python 3.7.4
• Operating System: macOS 10.15.2 (Catalina)

Description

I’m trying to write an application that uses tkinter and bleak to discover and interact with a custom BLE device. However, when I try to connect to the device, it throws an exception:

'NoneType' object has no attribute 'delegate'
  File ".../scratch.py", line 29, in run
    await client.connect()
  File ".../miniconda3/envs/py3/lib/python3.8/site-packages/bleak/backends/corebluetooth/client.py", line 86, in connect
    manager = self._device_info.manager().delegate()

(There is also a similar exception thrown in the final clause when attempting to disconnect)

I have condensed this to the application shown below.

import asyncio
import re
import traceback
import tkinter as tk
from bleak import BleakClient
from bleak import BleakScanner


async def run():
    if explicit:
        devices = await BleakScanner.discover(loop=loop)
    else:
        devices = await BleakScanner.discover()

    for d in devices:
        print(d)

    matcher = re.compile(r"[A-z]{3}-[0-9]{3}")
    devices = [d for d in devices if matcher.match(d.name)]
    if explicit:
        client = BleakClient(devices[0].address, loop=loop)
    else:
        client = BleakClient(devices[0].address)

    try:
        if explicit:
            await client.connect(loop=loop)
        else:
            await client.connect()
        print("Connected to {0}".format(client))
    except Exception as e:
        print(e)
        traceback.print_tb(e.__traceback__)
    finally:
        await client.disconnect()


def scan_and_connect():
    asyncio.get_event_loop().create_task(run())


async def update_ui():
    while True:
        root.update()
        await asyncio.sleep(1 / 30)


explicit = False  # Explicit or implicit run loops
loop = asyncio.get_event_loop()

root = tk.Tk()
if explicit:
    root.loop = loop
btn = tk.Button(root, text="Scan and connect", command=scan_and_connect)
btn.grid(column=1, row=1)

loop.run_until_complete(update_ui())

# Works as expected (i.e. connects to device)
# loop.run_until_complete(run())

What I Did

I’ve tried the following combinations:

Bleak	Loop	Outcome
v0.7.1	Implicit	Exception
v0.7.1	Explicit	Exception
v0.8.0	Implicit	Exception
v0.8.0	Explicit	Exception

[0ge]

Works perfectly! 👌 Both connecting and disconnecting works with tkinter now. I’ll continue testing next week with reading, writing and notifications.

[dlech]

Thanks @0ge and @Carglglz for all of the investigation and testing to get to the bottom of the issue!