pyo3/README.md
2018-05-30 15:03:31 +02:00

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# PyO3
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[Rust](http://www.rust-lang.org/) bindings for the [Python](https://www.python.org/) interpreter. This includes running and interacting with python code from a rust binaries as well as writing native python modules.
* [User Guide](https://pyo3.github.io/pyo3/guide/)
* [API Documentation](http://pyo3.github.io/pyo3/pyo3/)
A comparison with rust-cpython can be found [in the guide](https://pyo3.github.io/pyo3/guide/rust-cpython.html).
## Usage
Pyo3 supports python 2.7 as well as python 3.5 and up. The minimum required rust version is 1.27.0-nightly 2018-05-01.
### From a rust binary
To use `pyo3`, add this to your `Cargo.toml`:
```toml
[dependencies]
pyo3 = "0.2"
```
Example program displaying the value of `sys.version`:
```rust
#![feature(proc_macro, 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(())
}
```
### As native module
Pyo3 can be used to write native python module. The example will generate a python-compatible library.
For MacOS, "-C link-arg=-undefined -C link-arg=dynamic_lookup" is required to build the library.
`setuptools-rust` includes this by default. See [examples/word-count](examples/word-count) and the associated setup.py. 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.
**`Cargo.toml`:**
```toml
[lib]
name = "rust2py"
crate-type = ["cdylib"]
[dependencies.pyo3]
version = "0.2"
features = ["extension-module"]
```
**`src/lib.rs`**
```rust
#![feature(proc_macro, specialization)]
extern crate pyo3;
use pyo3::prelude::*;
use pyo3::py::modinit;
// Add bindings to the generated python module
// N.B: names: "librust2py" must be the name of the `.so` or `.pyd` file
/// This module is implemented in Rust.
#[modinit(rust2py)]
fn init_mod(py: Python, m: &PyModule) -> PyResult<()> {
#[pyfn(m, "sum_as_string")]
// ``#[pyfn()]` converts the arguments from Python objects to Rust values
// and the Rust return value back into a Python object.
fn sum_as_string_py(a:i64, b:i64) -> PyResult<String> {
let out = sum_as_string(a, b);
Ok(out)
}
Ok(())
}
// The logic can be implemented as a normal rust function
fn sum_as_string(a:i64, b:i64) -> String {
format!("{}", a + b).to_string()
}
```
For `setup.py` integration, see [setuptools-rust](https://github.com/PyO3/setuptools-rust)
## License
PyO3 is licensed under the [Apache-2.0 license](http://opensource.org/licenses/APACHE-2.0).
Python is licensed under the [Python License](https://docs.python.org/2/license.html).