# lib.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.13.2/src/lib.rs`.
Keywords: rust, rustlang, rust-lang

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    #![cfg_attr(feature = "nightly", feature(specialization))]
    #![allow(clippy::missing_safety_doc)] // FIXME (#698)

    //! Rust bindings to the Python interpreter.
    //!
    //! Look at [the guide](https://pyo3.rs/) 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](https://pyo3.rs/master/types.html) 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`**
    //!
    //! ```toml
    //! [package]
    //! name = "string-sum"
    //! version = "0.1.0"
    //! edition = "2018"
    //!
    //! [lib]
    //! name = "string_sum"
    //! # "cdylib" is necessary to produce a shared library for Python to import from.
    //! #
    //! # Downstream Rust code (including code in `bin/`, `examples/`, and `tests/`) will not be able
    //! # to `use string_sum;` unless the "rlib" or "lib" crate type is also included, e.g.:
    //! # crate-type = ["cdylib", "rlib"]
    //! crate-type = ["cdylib"]
    //!
    //! [dependencies.pyo3]
    //! version = "0.13.2"
    //! features = ["extension-module"]
    //! ```
    //!
    //! **`src/lib.rs`**
    //!
    //! ```rust
    //! 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:
    //!
    //! ```toml
    //! [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](https://github.com/PyO3/maturin) or
    //! [setuptools-rust](https://github.com/PyO3/setuptools-rust). You can find an
    //! example for setuptools-rust in [examples/word-count](examples/word-count),
    //! while maturin should work on your crate without any configuration.
    //!
    //! ## Using Python from Rust
    //!
    //! Add `pyo3` to your `Cargo.toml`:
    //!
    //! ```toml
    //! [dependencies.pyo3]
    //! version = "0.13.2"
    //! features = ["auto-initialize"]
    //! ```
    //!
    //! Example program displaying the value of `sys.version`:
    //!
    //! ```rust
    //! 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(())
    //! }
    //! ```

    pub use crate::class::*;
    pub use crate::conversion::{
        AsPyPointer, FromPyObject, FromPyPointer, IntoPy, IntoPyPointer, PyTryFrom, PyTryInto,
        ToBorrowedObject, ToPyObject,
    };
    pub use crate::err::{PyDowncastError, PyErr, PyErrArguments, PyResult};
    #[cfg(all(Py_SHARED, not(PyPy)))]
    pub use crate::gil::{prepare_freethreaded_python, with_embedded_python_interpreter};
    pub use crate::gil::{GILGuard, GILPool};
    pub use crate::instance::{Py, PyNativeType, PyObject};
    pub use crate::pycell::{PyCell, PyRef, PyRefMut};
    pub use crate::pyclass::PyClass;
    pub use crate::pyclass_init::PyClassInitializer;
    pub use crate::python::{Python, PythonVersionInfo};
    pub use crate::type_object::{type_flags, PyTypeInfo};
    // Since PyAny is as important as PyObject, we expose it to the top level.
    pub use crate::types::PyAny;

    #[cfg(feature = "macros")]
    #[doc(hidden)]
    pub use {
        ctor,      // Re-exported for pyproto
        indoc,     // Re-exported for py_run
        inventory, // Re-exported for pymethods
        paste,     // Re-exported for wrap_function
        unindent,  // Re-exported for py_run
    };

    // The CPython stable ABI does not include PyBuffer.
    #[cfg(not(Py_LIMITED_API))]
    pub mod buffer;
    #[doc(hidden)]
    pub mod callback;
    pub mod class;
    pub mod conversion;
    #[macro_use]
    #[doc(hidden)]
    pub mod derive_utils;
    mod err;
    pub mod exceptions;
    /// Raw ffi declarations for the c interface of python
    #[allow(clippy::unknown_clippy_lints)]
    #[allow(clippy::missing_safety_doc)]
    pub mod ffi;
    pub mod freelist;
    mod gil;
    mod instance;
    #[macro_use]
    mod internal_tricks;
    #[cfg(not(Py_LIMITED_API))]
    pub mod marshal;
    pub mod once_cell;
    pub mod panic;
    pub mod prelude;
    pub mod pycell;
    pub mod pyclass;
    pub mod pyclass_init;
    pub mod pyclass_slots;
    mod python;
    pub mod type_object;
    pub mod types;

    #[cfg(feature = "serde")]
    pub mod serde;

    /// The proc macros, which are also part of the prelude.
    #[cfg(feature = "macros")]
    pub mod proc_macro {
        pub use pyo3_macros::pymodule;
        /// The proc macro attributes
        pub use pyo3_macros::{pyclass, pyfunction, pymethods, pyproto};
    }

    /// Returns a function that takes a [Python] instance and returns a Python function.
    ///
    /// Use this together with `#[pyfunction]` and [types::PyModule::add_wrapped].
    #[macro_export]
    macro_rules! wrap_pyfunction {
        ($function_name: ident) => {{
            &pyo3::paste::expr! { [<__pyo3_get_function_ $function_name>] }
        }};

        ($function_name: ident, $arg: expr) => {
            pyo3::wrap_pyfunction!($function_name)(pyo3::derive_utils::PyFunctionArguments::from($arg))
        };
    }

    /// Returns the function that is called in the C-FFI.
    ///
    /// Use this together with `#[pyfunction]` and [types::PyCFunction].
    /// ```
    /// use pyo3::prelude::*;
    /// use pyo3::types::PyCFunction;
    /// use pyo3::raw_pycfunction;
    ///
    /// #[pyfunction]
    /// fn some_fun() -> PyResult<()> {
    ///     Ok(())
    /// }
    ///
    /// #[pymodule]
    /// fn module(_py: Python, module: &PyModule) -> PyResult<()> {
    ///     let ffi_wrapper_fun = raw_pycfunction!(some_fun);
    ///     let docs = "Some documentation string with null-termination\0";
    ///     let py_cfunction =
    ///         PyCFunction::new_with_keywords(ffi_wrapper_fun, "function_name", docs, module.into())?;
    ///     module.add_function(py_cfunction)
    /// }
    /// ```
    #[macro_export]
    macro_rules! raw_pycfunction {
        ($function_name: ident) => {{
            pyo3::paste::expr! { [<__pyo3_raw_ $function_name>] }
        }};
    }

    /// Returns a function that takes a [Python] instance and returns a Python module.
    ///
    /// Use this together with `#[pymodule]` and [types::PyModule::add_wrapped].
    #[macro_export]
    macro_rules! wrap_pymodule {
        ($module_name:ident) => {{
            pyo3::paste::expr! {
                &|py| unsafe { pyo3::PyObject::from_owned_ptr(py, [<PyInit_ $module_name>]()) }
            }
        }};
    }

    /// A convenient macro to execute a Python code snippet, with some local variables set.
    ///
    /// # Example
    /// ```
    /// use pyo3::{prelude::*, py_run, types::PyList};
    /// let gil = Python::acquire_gil();
    /// let py = gil.python();
    /// let list = PyList::new(py, &[1, 2, 3]);
    /// py_run!(py, list, "assert list == [1, 2, 3]");
    /// ```
    ///
    /// You can use this macro to test pyfunctions or pyclasses quickly.
    ///
    /// # Example
    /// ```
    /// use pyo3::{prelude::*, py_run, PyCell};
    /// #[pyclass]
    /// #[derive(Debug)]
    /// struct Time {
    ///     hour: u32,
    ///     minute: u32,
    ///     second: u32,
    /// }
    /// #[pymethods]
    /// impl Time {
    ///     fn repl_japanese(&self) -> String {
    ///         format!("{}時{}分{}秒", self.hour, self.minute, self.second)
    ///     }
    ///     #[getter]
    ///     fn hour(&self) -> u32 {
    ///         self.hour
    ///     }
    ///     fn as_tuple(&self) -> (u32, u32, u32) {
    ///         (self.hour, self.minute, self.second)
    ///     }
    /// }
    /// let gil = Python::acquire_gil();
    /// let py = gil.python();
    /// let time = PyCell::new(py, Time {hour: 8, minute: 43, second: 16}).unwrap();
    /// let time_as_tuple = (8, 43, 16);
    /// py_run!(py, time time_as_tuple, r#"
    /// assert time.hour == 8
    /// assert time.repl_japanese() == "8時43分16秒"
    /// assert time.as_tuple() == time_as_tuple
    /// "#);
    /// ```
    ///
    /// **Note**
    /// Since this macro is intended to use for testing, it **causes panic** when
    /// [Python::run] returns `Err` internally.
    /// If you need to handle failures, please use [Python::run] directly.
    ///
    #[macro_export]
    #[cfg(feature = "macros")]
    macro_rules! py_run {
        ($py:expr, $($val:ident)+, $code:literal) => {{
            $crate::py_run_impl!($py, $($val)+, $crate::indoc::indoc!($code))
        }};
        ($py:expr, $($val:ident)+, $code:expr) => {{
            $crate::py_run_impl!($py, $($val)+, &$crate::unindent::unindent($code))
        }};
    }

    #[macro_export]
    #[doc(hidden)]
    #[cfg(feature = "macros")]
    macro_rules! py_run_impl {
        ($py:expr, $($val:ident)+, $code:expr) => {{
            use $crate::types::IntoPyDict;
            use $crate::ToPyObject;
            let d = [$((stringify!($val), $val.to_object($py)),)+].into_py_dict($py);

            if let Err(e) = $py.run($code, None, Some(d)) {
                e.print($py);
                // So when this c api function the last line called printed the error to stderr,
                // the output is only written into a buffer which is never flushed because we
                // panic before flushing. This is where this hack comes into place
                $py.run("import sys; sys.stderr.flush()", None, None)
                    .unwrap();
                panic!($code.to_string())
            }
        }};
    }

    /// Test readme and user guide
    #[doc(hidden)]
    pub mod doc_test {
        macro_rules! doc_comment {
            ($x:expr, $module:item) => {
                #[doc = $x]
                $module
            };
        }

        macro_rules! doctest {
            ($x:expr, $y:ident) => {
                doc_comment!(include_str!($x), mod $y {});
            };
        }

        doctest!("../README.md", readme_md);
        doctest!("../guide/src/advanced.md", guide_advanced_md);
        doctest!(
            "../guide/src/building_and_distribution.md",
            guide_building_and_distribution_md
        );
        doctest!(
            "../guide/src/building_and_distribution/pypy.md",
            guide_building_and_distribution_pypy_md
        );
        doctest!("../guide/src/class.md", guide_class_md);
        doctest!("../guide/src/class/protocols.md", guide_class_protocols_md);
        doctest!("../guide/src/conversions.md", guide_conversions_md);
        doctest!(
            "../guide/src/conversions/tables.md",
            guide_conversions_tables_md
        );
        doctest!(
            "../guide/src/conversions/traits.md",
            guide_conversions_traits_md
        );
        doctest!("../guide/src/debugging.md", guide_debugging_md);
        doctest!("../guide/src/exception.md", guide_exception_md);
        doctest!("../guide/src/function.md", guide_function_md);
        doctest!("../guide/src/migration.md", guide_migration_md);
        doctest!("../guide/src/module.md", guide_module_md);
        doctest!("../guide/src/parallelism.md", guide_parallelism_md);
        doctest!(
            "../guide/src/python_from_rust.md",
            guide_python_from_rust_md
        );
        doctest!("../guide/src/rust_cpython.md", guide_rust_cpython_md);
        doctest!("../guide/src/trait_bounds.md", guide_trait_bounds_md);
        doctest!("../guide/src/types.md", guide_types_md);
    }

    // interim helper until #[cfg(panic = ...)] is stable
    #[cfg(test)]
    fn cfg_panic_unwind() -> bool {
        option_env!("RUSTFLAGS").map_or(true, |var| !var.contains("-Cpanic=abort"))
    }