Example that embeds CPython via libpython into a Wasm module written in Rust.
Uses the cpython crate. For disambiguation purposes, let's note that this crate offers Rust bindings for the C API by CPython and is not part of the official CPython implementation.
Take a look at the similar example in ../wasi-py-rs-pyo3 to see how this works with the pyo3 crate, which is an alternative to cpython that also provides Rust bindings on top of the C API implemented by libpython.
Make sure you have cargo with the wasm32-wasi target. For running we use wasmtime, but the module will work with any WASI-compliant runtime.
Just run ./run_me.sh in the current folder. You will see something like this
wlr/python/examples/embedding/wasi-py-rs-cpython $$ ./run_me.sh
Compiling cpython v0.7.1
...
Finished dev [unoptimized + debuginfo] target(s) in 26.43s
Calling a WASI Command which demonstrates usage of the 'cpython' crate :
+ wasmtime --mapdir /usr::target/wasm32-wasi/wasi-deps/usr target/wasm32-wasi/debug/wasi-py-rs-cpython.wasm
Hello! I'm Python 3.11.3 (tags/v3.11.3:f3909b8, Apr 28 2023, 09:45:45) [Clang 15.0.7 ], running on wasi/posix
+ set +x
The code is adapted from cpython crate's docs.
For cpython to work the final binary needs to link to libpython3.11.a. To get a wasm32-wasi version of libpython we provide a helper crate wlr-libpy, which can be used to fetch the pre-built library that this repository publishes.
Note that the cpython crate's build requires that python3 is installed on the build machine (even if we actually link to the wasm32-wasi libpython fetched by wlr-libpy).
The build process and dependencies are described in detail with the similar example in ../wasi-py-rs-pyo3.