Trait cpython::RefFromPyObject[][src]

pub trait RefFromPyObject {
    fn with_extracted<F, R>(py: Python<'_>, obj: &PyObject, f: F) -> PyResult<R>
        F: FnOnce(&Self) -> R
; }

RefFromPyObject is implemented by various types that can be extracted as a reference from a Python object. Depending on the input object, the reference may point into memory owned by the Python interpreter; or into a temporary object.

let sum_of_bytes = <[u8] as RefFromPyObject>::with_extracted(py, obj,
    |data: &[u8]| data.iter().sum()

A lambda has to be used because the slice may refer to temporary object that exists only during the with_extracted call.

Each target type for this conversion supports a different Python objects as input. Calls with an unsupported input object will result in an exception (usually a TypeError).

This trait is also used by the py_fn! and py_class! and py_argparse! macros in order to translate from Python objects to the expected Rust parameter types. For example, the parameter x in def method(self, x: &[u8]) will use impl RefFromPyObject for [u8] to convert the input Python object into a Rust &[u8]. When these macros are used with non-reference parameters (x: i32), the trait FromPyObject is used instead.

Required methods

fn with_extracted<F, R>(py: Python<'_>, obj: &PyObject, f: F) -> PyResult<R> where
    F: FnOnce(&Self) -> R, 

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Implementations on Foreign Types

impl RefFromPyObject for str[src]

Allows extracting strings from Python objects. Accepts Python str and unicode objects. In Python 2.7, str is expected to be UTF-8 encoded.

impl RefFromPyObject for [u8][src]

For Python bytes, returns a reference to the existing immutable string data. If the Python object is a single-dimensional buffer of format c or B (C: char or unsigned char), returns an owned copy of the data in the buffer. Otherwise, uses the sequence protocol and converts each individual element via impl FromPyObject for u8.

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impl<T: ?Sized> RefFromPyObject for T where
    &'a T: FromPyObject<'a>, 

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