integration between Python and Rust - Part 1

Let’s get our feet wet; in this first part I’ll write about a very simple way to interface Rust and Python. First of all let’s build a Rust dynamic library with some basic functions.

// this file is: src/lib.rs

#[no_mangle]
pub extern "C" fn hello() {
    println!("Hello from the library!");
}

#[no_mangle]
pub extern "C" fn sum(a: i32, b: i32) -> i32 {
    a + b
}

your Cargo.toml should look like this:

[package]
name = "pyrust"
version = "0.1.0"
edition = "2018"

[dependencies]

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

compile the library with cargo build

now we need a trivial python program to test our library:

import ctypes
lib=ctypes.PyDLL("target/debug/libpyrust.so")
lib.hello()
c=lib.sum(3,4)
print(c)

running it, we get the expected result:

$ python3 test_lib.py 
Hello from the library!
7

since we exported our functions from Rust as plain C, and we don’t make any fancy allocation or manipulation of Python objects, it’s pretty standard to use the library as it was written in C. In the next post we’ll explore more advanced options…