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: master

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 1.34.0-nightly 2019-02-06.

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

On some OSs, you need some additional packages.

E.g. if you are on Ubuntu18.04, please run

sudo apt install python3-dev python-dev

Using rust from python

PyO3 can be used to generate a native python module.

Cargo.toml

[package]
name = "string-sum"
version = "0.1.0"
edition = "2018"

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

[dependencies.pyo3]
version = "0.6.0-alpha.4"
features = ["extension-module"]

src/lib.rs

// Not required when using Rust 2018
extern crate pyo3;

use pyo3::prelude::*;
use pyo3::wrap_pyfunction;

#[pyfunction]
/// Formats the sum of two numbers as string
fn sum_as_string(a: usize, b: usize) -> PyResult<String> {
    Ok((a + b).to_string())
}

/// This module is a python module implemented in Rust.
#[pymodule]
fn string_sum(py: Python, m: &PyModule) -> PyResult<()> {
    m.add_wrapped(wrap_pyfunction!(sum_as_string))?;

    Ok(())
}

On windows and linux, you can build normally with cargo build --release. On macOS, 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:

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

For developing, you can copy and rename the shared library from the target folder: On macOS, rename libstring_sum.dylib to string_sum.so, on windows libstring_sum.dll to string_sum.pyd and on linux libstring_sum.so to string_sum.so. Then open a python shell in the same folder and you'll be able to import string_sum.

To build, test and publish your crate as python module, you can use pyo3-pack or setuptools-rust. You can find an example for setuptools-rust in examples/word-count, while pyo3-pack should work on your crate without any configuration.

Using python from rust

Add pyo3 this to your Cargo.toml:

[dependencies]
pyo3 = "0.6.0-alpha.4"

Example program displaying the value of sys.version:

// Not required when using Rust 2018
extern crate pyo3;

use pyo3::prelude::*;
use pyo3::types::IntoPyDict;

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 = [("os", py.import("os")?)].into_py_dict(py);
    let code = "os.getenv('USER') or os.getenv('USERNAME') or 'Unknown'";
    let user: String = py.eval(code, None, Some(&locals))?.extract()?;
    println!("Hello {}, I'm Python {}", user, version);
    Ok(())
}

Examples and tooling

• examples/word-count Counting the occurrences 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
• html-py-ever Using html5ever through kuchiki to speed up html parsing and css-selecting.
• pyo3-built Simple macro to expose metadata obtained with the built crate as a PyDict
• point-process High level API for pointprocesses as a Python library
• autopy A simple, cross-platform GUI automation library for Python and Rust.
• orjson Fast Python JSON library

License

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