Trait pyo3::conversion::FromPyObject

source ·

pub trait FromPyObject<'source>: Sized {
    // Required method
    fn extract(ob: &'source PyAny) -> PyResult<Self>;

    // Provided method
    fn type_input() -> TypeInfo { ... }
}

Expand description

Extract a type from a Python object.

Normal usage is through the extract methods on Py and PyAny, which forward to this trait.

Examples

use pyo3::prelude::*;
use pyo3::types::PyString;

Python::with_gil(|py| {
    let obj: Py<PyString> = PyString::new(py, "blah").into();

    // Straight from an owned reference
    let s: &str = obj.extract(py)?;

    // Or from a borrowed reference
    let obj: &PyString = obj.as_ref(py);
    let s: &str = obj.extract()?;
})

Note: depending on the implementation, the lifetime of the extracted result may depend on the lifetime of the obj or the prepared variable.

For example, when extracting &str from a Python byte string, the resulting string slice will point to the existing string data (lifetime: 'source). On the other hand, when extracting &str from a Python Unicode string, the preparation step will convert the string to UTF-8, and the resulting string slice will have lifetime 'prepared. Since which case applies depends on the runtime type of the Python object, both the obj and prepared variables must outlive the resulting string slice.

The trait’s conversion method takes a &PyAny argument but is called FromPyObject for historical reasons.

Required Methods§

source

fn extract(ob: &'source PyAny) -> PyResult<Self>

Extracts Self from the source PyObject.

Provided Methods§

source

fn type_input() -> TypeInfo

Extracts the type hint information for this type when it appears as an argument.

For example, Vec<u32> would return Sequence[int]. The default implementation returns Any, which is correct for any type.

For most types, the return value for this method will be identical to that of IntoPy::type_output. It may be different for some types, such as Dict, to allow duck-typing: functions return Dict but take Mapping as argument.

Trait pyo3::conversion::FromPyObject

Examples

Required Methods§

fn extract(ob: &'source PyAny) -> PyResult<Self>

Provided Methods§

fn type_input() -> TypeInfo

Implementations on Foreign Types§

impl<'a, T> FromPyObject<'a> for Vec<T>where T: FromPyObject<'a>,

fn extract(obj: &'a PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl FromPyObject<'_> for OsString

fn extract(ob: &PyAny) -> PyResult<Self>

impl<'source> FromPyObject<'source> for NonZeroUsize

fn extract(obj: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for i128

fn extract(ob: &'source PyAny) -> PyResult<i128>

fn type_input() -> TypeInfo

impl<'s, T0: FromPyObject<'s>, T1: FromPyObject<'s>> FromPyObject<'s> for (T0, T1)

fn extract(obj: &'s PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl FromPyObject<'_> for NaiveTime

fn extract(ob: &PyAny) -> PyResult<NaiveTime>

impl<'source> FromPyObject<'source> for usize

fn extract(obj: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for f64

fn extract(obj: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl FromPyObject<'_> for char

fn extract(obj: &PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source, K> FromPyObject<'source> for BTreeSet<K>where K: FromPyObject<'source> + Ord,

fn extract(ob: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for &'source str

fn extract(ob: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for Cow<'source, [u8]>

fn extract(ob: &'source PyAny) -> PyResult<Self>

impl FromPyObject<'_> for Decimal

fn extract(obj: &PyAny) -> PyResult<Self>

impl<'source, K, V, S> FromPyObject<'source> for HashMap<K, V, S>where K: FromPyObject<'source> + Eq + Hash, V: FromPyObject<'source>, S: BuildHasher + Default,

fn extract(ob: &'source PyAny) -> Result<Self, PyErr>

fn type_input() -> TypeInfo

impl<'a, T> FromPyObject<'a> for Option<T>where T: FromPyObject<'a>,

fn extract(obj: &'a PyAny) -> PyResult<Self>

impl<'source, K, V, S> FromPyObject<'source> for IndexMap<K, V, S>where K: FromPyObject<'source> + Eq + Hash, V: FromPyObject<'source>, S: BuildHasher + Default,

fn extract(ob: &'source PyAny) -> Result<Self, PyErr>

impl FromPyObject<'_> for Duration

fn extract(ob: &PyAny) -> PyResult<Duration>

impl<'source> FromPyObject<'source> for Complex<f64>

fn extract(obj: &'source PyAny) -> PyResult<Complex<f64>>

fn extract(obj: &'s PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for NonZeroI128

fn extract(obj: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for u8

fn extract(obj: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

fn extract(obj: &'s PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for u32

fn extract(obj: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'a, T: FromPyObject<'a>> FromPyObject<'a> for Cell<T>

fn extract(ob: &'a PyAny) -> PyResult<Self>

impl<'source> FromPyObject<'source> for Complex<f32>

fn extract(obj: &'source PyAny) -> PyResult<Complex<f32>>

impl<'source> FromPyObject<'source> for u128

fn extract(ob: &'source PyAny) -> PyResult<u128>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for NonZeroI8

fn extract(obj: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl<'source> FromPyObject<'source> for f32

fn extract(obj: &'source PyAny) -> PyResult<Self>

fn type_input() -> TypeInfo

impl FromPyObject<'_> for Utc