ritual VS cxx

For your inspiration to get c++ code in a crate: https://github.com/rust-qt/examples uses ritual build https://github.com/rust-qt/ritual which integrates qt c++ stuff into the above cargo qt rust examples. I would like to highlight the todo list example. Build and run it verbosely with "--verbose --verbose".

It is great to see how many people want to bring Qt support to Rust and are trying to do so, and I hope that these folks succeed, but it’s wearisome to me how they each create a new project instead of working with others who are already in this problem space. Of the half-dozen or so[0] existing attempts so far to create Qt bindings to Rust, none of them have actually succeeded because they’ve either been abandoned midway or limit their support to QML. Ritual[1] is the only crate I’ve seen that attempts to actually expose the whole Qt API, but it’s pretty awful to use, incomplete, and dead.

Rust doesn’t need more Qt crates. It needs one Qt crate that is complete and works well. (Or, ideally, a native Rust cross-platform GUI crate that works as well as Qt, but that’s an even longer and harder task.)

[0] https://lib.rs/search?q=qt

[1] https://github.com/rust-qt/ritual

Just wanted to add another vote for https://github.com/rust-qt/ritual that 0OOO00000OO00O0O0OOO/ mentioned below.

There was a QT library, rust-qt (that was officially supported I believe), the bindings being made with Ritual. There is an open issue for supporting qt6, which I'm also awaiting; https://github.com/rust-qt/ritual/issues/109.

There are cxx and autocxx, what else do you propose to do?

I would like to see a comparison of how this compares to Rust. In terms of interoperability it has Cxx (https://cxx.rs) to offer safe bindings to C++ but also has great support for Android, Linux and many other systems. You don't even need to hack together Windows bindings (as explained in the blog post) because Microsoft offers official bindings (https://crates.io/crates/windows). I'm not sure if I'd call it a superpower if any potential interoperability has to be written to be used (compared to it already being available). Or rather, in comparison to what is interoperability a Swift superpower? Certainly not C++ or C which can be used in a far wider set of targets.

We selected Qt as a cross-platform solution. The C++/Rust interface is the clunkiest and ugliest part of the application, and rather complex because some state is shared between several windows in the GUI and several threads in the backend, and any component might modify that state at any time, and updates have to be transmitted to the other components without introducing inconsistencies. Using cxx [1] helped a little, though.

The project began in 2020, and I'm not sure what I'd choose as a GUI framework today – definitely not Qt Widgets, though.

[1] https://cxx.rs/

If the build process for the C library isn't too involved I recommend using cxx bridge (https://cxx.rs/) and letting cargo handle the build and linking. cxx basically allows you to describe the bidirectional interface (although it sounds like you only need 1 direction, which is fine too) in Rust code and it provides a "good enough" API for compiling C code inside the build.rs file.

The tooling for the first kind -- calling Rust from another language -- is a bit less developed, and tends to rely on code generation that doesn't necessarily produce a natural C API. cbindgen, uniffi, cxx, and Diplomat all take this course.

I would like to utilize OMPL's functionality in Rust code, so I want to call into OMPL C++ code somehow in Rust. I've seen two (non-mutually-exclusive) options so far: - rust-cpp, which allows you to write C++ code in Rust within the cpp!() macro. - cxx, which allows you to define both sides of the FFI boundary manually (as opposed to bindgen's automatic generation).

I'm not sure how to do this in cxx; issues like https://github.com/dtolnay/cxx/issues/447 suggest that this isn't settled yet?

I use non-vendored dependencies for the Buck build in https://github.com/dtolnay/cxx.

There's also the cpp and cxx crates for doing C++/Rust interop, but they probably aren't appropriate to use in all cases. The C ABI is definitely the safest way to go unless you're really trying to marry Rust and C++ code bases, not just writing library bindings.

There's also cxx (can't vouch for it personally but it claims to make things a lot easier) https://github.com/dtolnay/cxx