https://github.com/dropbox/pyannotate

Auto-generate PEP-484 annotations

PyAnnotate: Auto-generate PEP-484 annotations

Insert annotations into your source code based on call arguments and return types observed at runtime.

For license and copyright see the end of this file.

How to use

See also the example directory.

Phase 1: Collecting types at runtime

• Install the usual way (see "red tape" section below)
• Add from pyannotate_runtime import collect_types to your test
• Early in your test setup, call collect_types.init_types_collection()
• Bracket your test code between calls to collect_types.resume() and collect_types.pause()
• When done, call collect_types.dump_stats(filename)

All calls between the pause() and resume() calls will be analyzed and the observed types will be written (in JSON form) to the filename you pass to dump_stats(). You can have multiple pause/resume pairs per dump call.

Phase 2: Inserting types into your source code

The command-line tool pyannotate can add annotations into your source code based on the annotations collected in phase 1. The key arguments are:

• Use --type-info FILE to tell it the file you passed to dump_stats()
• Positional arguments are source files you want to annotate
• With no other flags the tool will print a diff indicating what it proposes to do but won't do anything. Review the output.
• Add -w to make the tool actually update your files. (Use git or some other way to keep a backup.)

At this point you should probably run mypy and iterate. You probably will have to tweak the changes to make mypy completely happy.

Notes and tips

• It's best to do one file at a time, at least until you're comfortable with the tool.
• The tool doesn't touch functions that already have an annotation.
• The tool currently always generates type comments, i.e. Python 2 style annotations. (Python 3 style are a TO DO item.)

Red tape

Installation

This should work for Python 2.7 as well as for Python 3.6 and higher. (It works for Python 3.4 and 3.5 as well, except for Python 3.5.1.)

pip install pyannotate

This installs several items:

• A runtime module, pyannotate_runtime/collect_types.py, which collects and dumps types observed at runtime using a profiling hook.

• A library package, pyannotate_tools, containing code that can read the data dumped by the runtime module and insert annotations into your source code.

• An entry point, pyannotate, which runs the library package on your files.

For dependencies, see setup.py and requirements.txt.

Testing etc.

To run the unit tests, use pytest:

pytest

TO DO

We'd love your help with some of these issues:

• Better documentation.
• Python 3 code generation.
• Refactor the tool modules (currently its legacy architecture shines through).

Acknowledgments

The following people contributed significantly to this tool:

• Tony Grue
• Sergei Vorobev
• Jukka Lehtosalo
• Guido van Rossum

Licence etc.

1. License: Apache 2.0.
2. Copyright attribution: Copyright (c) 2017 Dropbox, Inc.
3. External contributions to the project should be subject to Dropbox's Contributor License Agreement (CLA): https://opensource.dropbox.com/cla/