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Interoptopus 🐙

Extensible, lightweight, convenient FFI bindings for any^* language calling Rust.

Escape hatchets included. 🪓

^* C#, C, Python provided. Add yours in 4 hours. No pull request needed.

Code you write ...

```rust use interoptopus::{ffifunction, ffitype, inventory_function};

[ffi_type]

[repr(C)]

pub struct Vec2 { pub x: f32, pub y: f32, }

[ffi_function]

[no_mangle]

pub extern "C" fn my_function(input: Vec2) { println!("{}", input.x); }

inventoryfunction!(ffiinventory, [], [my_function], []); ```

... Interoptopus generates

| Language | Crate | Sample Output | | --- | --- | --- | | C# (incl. Unity) | interoptopusbackendcsharp | Interop.cs | | C | interoptopusbackendc | myheader.h | | Python CFFI | interoptopusbackendcpythoncffi | reference.py | | Your language | Write your own backend! | - |

Getting Started 🍼

If you ... - want to create a new API see the example projects, - need to support a new language or rewrite a backend, copy and adapt the C backend.

Features

• explicit, type-safe, single source of truth API definition in Rust,
• minimal on dependencies, build time, tooling impact
• if your project compiles your bindings should work<sup>TM, *cough*</sup> (i.e., generated and callable)
• extensible, multiple backends, easy to support new languages, or totally change existing ones
• quality-of-life patterns on both sides (e.g., options, slices, services, ...)
• doesn't need build scripts, cargo build + cargo test can produce and test (if lang installed) generated bindings

Supported Rust Constructs

See the reference project; it lists all supported constructs including: - functions (extern "C" functions and delegates) - types (primitives, composite, enums (numeric only), opaques, references, pointers, ...) - constants (primitive constants; results of const evaluation) - patterns (ASCII pointers, options, slices, classes, ...)

As a rule of thumb we recommend to be slightly conservative with your signatures and always "think C", since other languages don't track lifetimes well and it's is easy to accidentally pass an outlived pointer or doubly alias a &mut X on reentrant functions.

Current Status

• June 20, 2021 - Alpha. Has generated simple working<sup>TM</sup> bindings for a few projects for a week now, many things missing.
• June 13, 2021 - Pre-alpha. Has generated C#, C, Python-CFFI bindings at least once, many things missing, untested.

FAQ

• FAQ and Safety Guides.

Contributing

PRs are welcome.

• Bug fixes can be submitted directly. Major changes should be filed as issues first.

• Anything that would make previously working bindings change behavior or stop compiling is a major change; which doesn't mean we're opposed to breaking stuff before 1.0, just that we'd like to talk about it before it happens.

• New features or patterns must be materialized in the reference project and accompanied by an interop test (i.e., a backend test running C# / Python against a DLL invoking that code) in at least one included backend.