btleplug VS cxx

In case someone is curious: https://github.com/deviceplug/btleplug/pull/279/files

Is something wrong with https://github.com/deviceplug/btleplug or you haven't found it? You could also use bindings to platform libraries like https://github.com/microsoft/windows-rs and https://github.com/rust-mobile/ndk if btleplug doesn't have something fundamental to you.

One of the worst/best parts of buttplug is that I ended up needed to maintain my own Bluetooth LE library: btleplug (https://github.com/deviceplug/btleplug).

Worst because working with bluetooth is always THE WORST, best because of the submissions and community that've grown around it.

There's 2 types of PRs to btleplug:

- People going "here's a PR but uh, why is the library named btleplWAIT WHAT"

- People going "here is a PR specifically to fix something in Buttplug thank you"

"In its dev branch"

I've always been annoyed at the cross-platform story for Bluetooth. GATT is one of my favorite protocols because it is so simple, but writing simple code against this simple protocol is _not_ portable:

iOS and macOS have CoreBluetooth, Linux has BlueZ, Windows has Windows.Devices.Bluetooth and Android has android.bluetooth.

I've seen a few projects trying to fix this, like https://github.com/deviceplug/btleplug, and I hope one of them becomes production ready.

But, that's an ongoing problem. In terms of "done", I think the next big milestone will be mobile app support. We work on mobile web browsers in a couple of different ways, but Buttplug still needs app support, both native and for things like cordova/react native/etc... The biggest issue there at the moment lies in our bluetooth library (btleplug, https://github.com/deviceplug/btleplug), because getting the FFI via JNI to android is going to suck (even though I can crib off Servo's WebBluetooth impl, which worked on Android).

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

It’s not a conversion tool, but it does allow the strangulation pattern: cxx

I have a non-toy multi-language project in https://github.com/dtolnay/cxx for which I have both Buck2 and Bazel rules.

On my machine `buck2 clean && time buck2 build :cxx` takes 6.2 seconds.

`bazel clean && time bazel build :cxx` takes 19.9 seconds.