Crate pyo3[−][src]
Expand description
Rust bindings to the Python interpreter.
Look at the guide for a detailed introduction.
Ownership and Lifetimes
Because all Python objects potentially have multiple owners, the concept of Rust mutability does not apply to Python objects. As a result, PyO3 allows mutating Python objects even if they are not stored in a mutable Rust variable.
In Python, all objects are implicitly reference counted. The Python
interpreter uses a global interpreter lock (GIL) to ensure thread-safety.
Thus, we use struct Python<'py> as a token to indicate that
a function can assume that the GIL is held. In Rust, we use different types
to represent a reference to a Python object, depending on whether we know
the GIL is held, and depending on whether we know the underlying type. See
the guide for an explanation of
the different Python object types.
A Python instance is either obtained explicitly by acquiring the GIL,
or implicitly by PyO3 when it generates the wrapper code for Rust functions
and structs wrapped as Python functions and objects.
Error Handling
The vast majority of operations in this library will return PyResult<...>.
This is an alias for the type Result<..., PyErr>.
A PyErr represents a Python exception. Errors within the PyO3 library are
also exposed as Python exceptions.
Example
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 = "0.13.2"
features = ["extension-module"]src/lib.rs
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())
}
#[pymodule]
/// A Python module implemented in Rust.
fn string_sum(py: Python, m: &PyModule) -> PyResult<()> {
m.add_function(wrap_pyfunction!(sum_as_string, m)?)?;
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",
]
[target.aarch64-apple-darwin]
rustflags = [
"-C", "link-arg=-undefined",
"-C", "link-arg=dynamic_lookup",
]While developing, you symlink (or 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 a Python module, you can use maturin or setuptools-rust. You can find an example for setuptools-rust in examples/word-count, while maturin should work on your crate without any configuration.
Using Python from Rust
Add pyo3 to your Cargo.toml:
[dependencies.pyo3]
version = "0.13.2"
features = ["auto-initialize"]Example program displaying the value of sys.version:
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(())
}Re-exports
pub use crate::class::*;pub use crate::conversion::AsPyPointer;pub use crate::conversion::FromPyObject;pub use crate::conversion::FromPyPointer;pub use crate::conversion::IntoPy;pub use crate::conversion::IntoPyPointer;pub use crate::conversion::PyTryFrom;pub use crate::conversion::PyTryInto;pub use crate::conversion::ToBorrowedObject;pub use crate::conversion::ToPyObject;pub use crate::pycell::PyCell;pub use crate::pycell::PyRef;pub use crate::pycell::PyRefMut;pub use crate::pyclass::PyClass;pub use crate::pyclass_init::PyClassInitializer;pub use crate::type_object::type_flags;pub use crate::type_object::PyTypeInfo;Modules
PyBuffer implementation
Python object protocols
Conversions between various states of Rust and Python types and their wrappers.
Exception types defined by Python.
Raw ffi declarations for the c interface of python
Free allocation list
Support for the Python marshal format. Not supported in limited API
builds.
A collection of items you most likely want to have in scope when working with pyo3
The proc macros, which are also part of the prelude.
Includes PyCell implementation.
PyClass and related traits.
Initialization utilities for #[pyclass].
This module contains additional fields for #[pyclass]..
Mainly used by our proc-macro codes.
Python type object information
Various types defined by the Python interpreter such as int, str and tuple.
Macros
Defines a new exception type.
impl $crate::type_object::PyTypeObject for $name where $name is an
exception newly defined in Rust code.
The boilerplate to convert between a Rust type and a Python exception.
Defines a Rust type for an exception defined in Python code.
A convenient macro to execute a Python code snippet, with some local variables set.
Returns the function that is called in the C-FFI.
Returns a function that takes a Python instance and returns a Python function.
Returns a function that takes a Python instance and returns a Python module.
Structs
RAII type that represents the Global Interpreter Lock acquisition. To get hold of a value of
this type, see Python::acquire_gil.
A RAII pool which PyO3 uses to store owned Python references.
A Python object of known type T.
A Python object with GIL lifetime
Error that indicates a failure to convert a PyAny to a more specific Python type.
Represents a Python exception that was raised.
Marker type that indicates that the GIL is currently held.
Represents the major, minor, and patch (if any) versions of this interpreter.
Traits
Helper conversion trait that allows to use custom arguments for lazy exception construction.
Types that are built into the Python interpreter.
Functions
Prepares the use of Python in a free-threaded context.
Executes the provided closure with an embedded Python interpreter.