PyO3

Rust bindings for Python. This includes running and interacting with python code from a rust binaries as well as writing native python modules.

• User Guide: stable | master
• API Documentation

A comparison with rust-cpython can be found in the guide.

Usage

Pyo3 supports python 2.7 as well as python 3.5 and up. The minimum required rust version is 1.29.0-nightly 2018-07-16.

You can either write a native python module in rust or use python from a rust binary.

Using rust from python

Pyo3 can be used to generate a native python module.

Cargo.toml:

```toml [package] name = "rust-py" version = "0.1.0"

[lib] name = "rust_py" crate-type = ["cdylib"]

[dependencies.pyo3] version = "0.3" features = ["extension-module"] ```

src/lib.rs

```rust

![feature(useexternmacros, specialization)]

[macro_use]

extern crate pyo3;

use pyo3::prelude::*;

[pyfunction]

/// Formats the sum of two numbers as string fn sumasstring(a: usize, b: usize) -> PyResult { Ok((a + b).to_string()) }

/// This module is a python moudle implemented in Rust.

[pymodinit]

fn rustpy(py: Python, m: &PyModule) -> PyResult<()> { m.addfunction(wrapfunction!(sumas_string))?;

Ok(())

} ```

On windows and linux, you can build normally with cargo build --release. On Mac Os, you need to set additional linker arguments. One option is to compile with cargo rustc --release -- -C link-arg=-undefined -C link-arg=dynamic_lookup, the other is to create a .cargo/config with the following content:

toml [target.x86_64-apple-darwin] rustflags = [ "-C", "link-arg=-undefined", "-C", "link-arg=dynamic_lookup", ]

Also on macOS, you will need to rename the output from *.dylib to *.so. On Windows, you will need to rename the output from *.dll to *.pyd.

setuptools-rust can be used to generate a python package and includes the commands above by default. See examples/word-count and the associated setup.py.

Using python from rust

Add pyo3 this to your Cargo.toml:

toml [dependencies] pyo3 = "0.3"

Example program displaying the value of sys.version:

```rust

![feature(useexternmacros, specialization)]

extern crate pyo3;

use pyo3::prelude::*;

fn main() -> PyResult<()> { let gil = Python::acquire_gil(); let py = gil.python(); let sys = py.import("sys")?; let version: String = sys.get("version")?.extract()?;

let locals = PyDict::new(py);
locals.set_item("os", py.import("os")?)?;
let user: String = py.eval("os.getenv('USER') or os.getenv('USERNAME')", None, Some(&locals))?.extract()?;

println!("Hello {}, I'm Python {}", user, version);
Ok(())

} ```

Examples and tooling

• examples/word-count Counting the occurences of a word in a text file
• hyperjson A hyper-fast Python module for reading/writing JSON data using Rust's serde-json
• rust-numpy Rust binding of NumPy C-API
• pyo3-built Simple macro to expose metadata obtained with the built crate as a PyDict

License

PyO3 is licensed under the Apache-2.0 license. Python is licensed under the Python License.