Taskchampion Python bindings

[illya-laifu]

Hello,

Really appreciate your work on taskwarrior/taskchampion!

With the release of a new way to interact with the app (via the rust library), python bindings are needed. It's a big request, so I come bearing gifts - a fork with a POC barebones attempt to connect with an existing database instance and task creation here.

It's very much a barebones POC, with two methods, to get the impression of the workload needed; right now the code lives in the py-lib directory, and can be assembled via maturin.

Here's the demo in python console as an easy test:

Guess I am volunteering to work on this?

[djmitche]

That's fantastic! And, I think this approach looks good: interfacing directly from Python into the taskchampion crate. The taskchampion-lib crate was a bit of a mistake (soon to be replaced with use of CXX from Taskwarrior), so I'm glad you didn't choose to use that.

A few questions toward finding a way to make progress here;

• Is there an example you're following, embedding a Rust library in a Python app?
• How are PyO3 wrappers typically packaged and released? Are they usually developed in the same repo as the library?

Maybe a good next step is to get something that works into a PR and get that merged, with multiple TODO's scattered about. That can include README describing the intended implementation, and indicating that it's not yet stable or ready for use. Then we can get a few more issues filed and perhaps a few people can work on separate aspects in parallel.

[illya-laifu]

To answer your questions:

• I wasn't following any specific example, just what I saw in the taskchampion_lib crate as an inspiration, plus a healthy dose of docs from the pyo3. However, there are a number of crates that do could be used as an example, like tokenizers
• I am not sure about the best practices for the PyO3 packaging, the tokenizers put all their bindings in a single subfolder called bindings, but it is possible to do this standalone as well. Packaging is done via the same tool used to instantiate and build the project - maturin. On build is builds a wheel package, that can be uploaded to pypi via maturin publish, or by using other publishing tools.

[illya-laifu]

As per your suggestion, I will continue work in the forked repository, so we can possibly PR. This can be pulled into its own, separate repository later on, if need arises.

[djmitche]

Sounds good!

[illya-laifu]

Ok, I think I have the the core. I'll create PR in a bit, documenting the install/test process.

Currently implemented and tested:

• Annotation class and the getters/setters for the two fields.
• Replica class (::dependency_map method needs more testing and polishing due to the Rc reference)
• Status enum
• Tag class
• Task class *
• WorkingSet class

Implemented but not tested:

• DependencyMap class
• Storage concrete classes.

TODO:

• Be able to construct replica by passing in the specific Storage implementations (e.g. InMemoryStorage, SqliteStorage or users own implementation of Storage)
• Current Task class is the immutable version of it, it would be nice to extend it to also include the methods from TaskMut and convert to and the mutable state in those method calls. It is impossible to implement the TaskMut via pyo3 due to the lifetime parameters.*
• Be able to iterate over WorkingSet via next() and with for item in ws:, but this needs it to hold the reference to an iterator.
• Python has it's own uuid library, currently the methods that accept a UUID, do that by accepting str and converting it into the rust's implementation of UUID.
• Better documentation, but the Rust comments on the pyo3 annotated functions/objects directly translate into the docstrings.
• Not entirely sure if it is possible (need to research), but it would be convenient to provide signature stub files along with the library, so the LSP's, linters and such would be able to infer the types.

[djmitche]

This is really cool! I will try to take a look, but I've been quite busy so I invite anyone else following along to also jump in and offer feedback.

[illya-laifu]

Quick update on the todo items -- adding signature stub files is quite simple, just a bit tedious.