# txaio

txaio is a helper library for writing code that runs unmodified on both Twisted and asyncio / Trollius.

This is like six, but for wrapping over differences between Twisted and asyncio so one can write code that runs unmodified on both (aka source code compatibility). In other words: your users can choose if they want asyncio or Twisted as a dependency.

Note that, with this approach, user code runs under the native event loop of either Twisted or asyncio. This is different from attaching either one’s event loop to the other using some event loop adapter.

## Platform support

txaio runs on CPython 3.6+ and PyPy 3, on top of Twisted or asyncio. Specifically, txaio is tested on the following platforms:

- CPython 3.6 and 3.9 on Twisted 18.7, 19.10, trunk and on asyncio (stdlib)

- PyPy 3.6 an 3.7 on Twisted 18.7, 19.10, trunk and on asyncio (stdlib)

> Note: txaio up to version 18.8.1 also supported Python 2.7 and Python 3.4. Beginning with release v20.1.1, txaio only supports Python 3.5+. Beginning with release v20.12.1, txaio only supports Python 3.6+.

## How it works

Instead of directly importing, instantiating and using `Deferred` (for Twisted) or `Future` (for asyncio) objects, txaio provides helper-functions to do that for you, as well as associated things like adding callbacks or errbacks.

This obviously changes the style of your code, but then you can choose at runtime (or import time) which underlying event-loop to use. This means you can write one code-base that can run on Twisted or asyncio (without a Twisted dependency) as you or your users see fit.

Code like the following can then run on either system:

    import txaio
    txaio.use_twisted()  # or .use_asyncio()

    f0 = txaio.create_future()
    f1 = txaio.as_future(some_func, 1, 2, key='word')
    txaio.add_callbacks(f0, callback, errback)
    txaio.add_callbacks(f1, callback, errback)
    # ...
    txaio.resolve(f0, "value")
    txaio.reject(f1, RuntimeError("it failed"))

Please refer to the documentation for description and usage of the library features.

## AI Policy

> IMPORTANT: A Note on Upcoming Policy Changes Regarding AI-Assisted Content

> Up to and including release v25.6.1, this project contains no code or documentation generated with the assistance of AI tools. This version represents the final release under our historical contribution policy. Starting with future versions (after release v25.6.1), our contribution policy will change. Subsequent releases MAY contain code or documentation created with AI assistance.

We urge all users and contributors to review our AI Policy. This document details:

- The rules and warranties required for all future contributions.

- The potential intellectual property implications for the project and its users.

This policy was established following an open community discussion, which you can review on GitHub issue #1663.

We are providing this transparent notice to enable you to make an informed decision. If our new AI policy is incompatible with your own (or your organization’s) development practices or risk tolerance, please take this into consideration when deciding whether to upgrade beyond version v25.6.1.

# Contents

- Overview
  - Brief History
  - Overview by Example
  - Restrictions and Caveats
  - Futures and Deferreds
  - Callbacks and Errbacks
  - Error Handling
  - Real Examples
  - Cross-API Magic
- Programming Guide
  - Explict Event Loops
  - Logging
  - Logging Interoperability
  - Starting Logging Yourself
- Application Programming Interface
  - Explicitly Selecting a Framework
  - Set an Event Loop / Reactor
  - Test Helpers
  - txaio module
    - `using_twisted`
    - `using_asyncio`
    - `use_asyncio()`
    - `use_twisted()`
    - `create_future()`
    - `as_future()`
    - `reject()`
    - `cancel()`
    - `resolve()`
    - `add_callbacks()`
    - `failure_message()`
    - `failure_traceback()`
    - `call_later()`
    - `make_batched_timer()`
    - `gather()`
    - `make_logger()`
    - `ILogger`
    - `IFailedFuture`
- WAMP Projects Overview
  - The Group of Projects and WAMP
  - Important Files
    - Files Unified across Projects
    - Files Specific to each Project
- AI Disclosure Process
  - AI Disclosure Process: Purpose
  - 1. Issue Disclosures
  - 2. Pull Request (PR) Disclosures
  - 3. Disclosure File Format and Content
  - 4. Enforcement and Automation
  - 5. Git and Organizational Security
  - 6. Example Contributor Workflow
  - 7. Rationale
  - 8. Frequently Asked Questions
  - 9. Example Disclosure File
- AI Audit Process Review
  - User: Initial Question
  - Copilot: PR & Policy Review
    - 1. PR Summary & Context
    - 2. AI Policy, Disclosure, and Audit Tracking
    - 3. Audit “Hardness” & Evidence
    - 4. Process Review (Two-Phase Introduction)
    - 5. Recommendations & Comments
    - 6. Conclusion
  - User: Follow-Up (on how to make this public and verifiable)
  - Copilot: How to Publicly Archive the Conversation
    - 1. Manual Copy-Paste (most common)
    - 2. Attribution & Formatting Tips
    - 3. Alternative: Create a Gist or File
    - 4. Why This Works
    - Example
  - User: Follow-Up (on tamper-proofing and permalinks)
  - Copilot: On Immutability, Permalinks, and Alternatives
    - 1. Can you create a public, tamper-proof, shareable link to this conversation?
    - 2. Options for Maximum Auditability
    - 3. Why no public shareable link exists (yet)
  - User: Final Request
  - Copilot: (this file!)
  - User: Correction Request
  - Copilot: (this file, including your correction request)
- Package Releases
  - 25.6.1
  - 23.1.1
  - 22.2.1
  - 21.2.1
  - 20.12.1
  - 20.4.1
  - 20.3.1
  - 20.1.1
  - 18.8.1
  - 18.7.1
  - 2.10.0
  - 2.9.0
  - 2.8.2
  - 2.8.1
  - 2.8.0
  - 2.7.1
  - 2.7.0
  - 2.6.1
  - 2.6.0
  - 2.5.2
  - 2.5.1
  - 2.5.0
  - 2.4.0
  - 2.3.1
  - 2.3.0
  - previous releases