aiosignal

1.4.0 verified Tue May 12 auth: no python install: verified quickstart: verified

aiosignal is a Python library designed to manage asynchronous callbacks in asyncio projects. The current version is 1.4.0, released on July 3, 2025. The library has a moderate release cadence, with updates typically occurring annually.

pip install aiosignal

Common errors

error ModuleNotFoundError: No module named 'aiosignal' ↓

cause The 'aiosignal' package is not installed in the Python environment.

fix

pip install aiosignal

error ImportError: cannot import name 'Signal' from 'aiosignal' ↓

cause The 'Signal' class is not found in the 'aiosignal' module, possibly due to an incorrect import statement or version mismatch.

fix

from aiosignal import Signal

error TypeError: 'Signal' object is not callable ↓

cause Attempting to call a 'Signal' object as a function, which is not supported.

fix

Use 'await signal.send(data)' to trigger callbacks.

error AttributeError: 'Signal' object has no attribute 'append' ↓

cause Trying to use list methods like 'append' on a 'Signal' object, which does not support them.

fix

Use 'signal.connect(callback)' to add callbacks.

error RuntimeError: Cannot modify frozen signal ↓

cause Attempting to modify a 'Signal' object after it has been frozen.

fix

Ensure modifications are made before calling 'signal.freeze()'.

Warnings

breaking Dropped support for Python 3.7 and 3.8. ↓

fix Upgrade your Python environment to version 3.9 or newer.

gotcha Once a Signal is frozen, adding or removing callbacks is forbidden. ↓

fix Ensure all necessary callbacks are added before calling freeze().

gotcha Callbacks must be asynchronous functions. ↓

fix Define callbacks using async def.

Install compatibility verified last tested: 2026-05-12

python os / libc status wheel install import disk

3.10 alpine (musl) - - 0.03s 18.7M

3.10 slim (glibc) - - 0.02s 19M

3.11 alpine (musl) - - 0.07s 20.6M

3.11 slim (glibc) - - 0.05s 21M

3.12 alpine (musl) - - 0.05s 12.5M

3.12 slim (glibc) - - 0.06s 13M

3.13 alpine (musl) - - 0.01s 11.8M

3.13 slim (glibc) - - 0.01s 12M

3.9 alpine (musl) - - 0.03s 18.2M

3.9 slim (glibc) - - 0.02s 19M

Imports

Signal
wrong
```
from aiosignal.signal import Signal
```
correct
```
from aiosignal import Signal
```
The correct import is directly from the aiosignal package; importing from submodules is incorrect.

Quickstart verified last tested: 2026-04-23

This example demonstrates creating a Signal, registering a callback, freezing the signal, and sending data to the callback.

import asyncio
from aiosignal import Signal

async def callback(data):
    print(f'Received data: {data}')

async def main():
    signal = Signal(owner=None)
    signal.append(callback)
    signal.freeze()
    await signal.send('Hello, World!')

asyncio.run(main())