Struct pyo3::types::PyByteArray

#[repr(transparent)]
pub struct PyByteArray(_);

Represents a Python bytearray.

Implementations

impl PyByteArray

pub fn new<'p>(py: Python<'p>, src: &[u8]) -> &'p PyByteArray

Creates a new Python bytearray object.

The byte string is initialized by copying the data from the &[u8].

pub fn new_with<F>( py: Python<'_>, len: usize, init: F ) -> PyResult<&PyByteArray>where F: FnOnce(&mut [u8]) -> PyResult<()>,

Creates a new Python bytearray object with an init closure to write its contents. Before calling init the bytearray is zero-initialised.

• If Python raises a MemoryError on the allocation, new_with will return it inside Err.
• If init returns Err(e), new_with will return Err(e).
• If init returns Ok(()), new_with will return Ok(&PyByteArray).

Examples

use pyo3::{prelude::*, types::PyByteArray};

Python::with_gil(|py| -> PyResult<()> {
    let py_bytearray = PyByteArray::new_with(py, 10, |bytes: &mut [u8]| {
        bytes.copy_from_slice(b"Hello Rust");
        Ok(())
    })?;
    let bytearray: &[u8] = unsafe { py_bytearray.as_bytes() };
    assert_eq!(bytearray, b"Hello Rust");
    Ok(())
})

pub fn from(src: &PyAny) -> PyResult<&PyByteArray>

Creates a new Python bytearray object from another Python object that implements the buffer protocol.

pub fn len(&self) -> usize

Gets the length of the bytearray.

pub fn is_empty(&self) -> bool

Checks if the bytearray is empty.

pub fn data(&self) -> *mut u8

Gets the start of the buffer containing the contents of the bytearray.

Safety

See the safety requirements of PyByteArray::as_bytes and PyByteArray::as_bytes_mut.

pub unsafe fn as_bytes(&self) -> &[u8]

Extracts a slice of the ByteArray’s entire buffer.

Safety

Mutation of the bytearray invalidates the slice. If it is used afterwards, the behavior is undefined.

These mutations may occur in Python code as well as from Rust:

• Calling methods like PyByteArray::as_bytes_mut and PyByteArray::resize will invalidate the slice.
• Actions like dropping objects or raising exceptions can invoke __del__methods or signal handlers, which may execute arbitrary Python code. This means that if Python code has a reference to the bytearray you cannot safely use the vast majority of PyO3’s API whilst using the slice.

As a result, this slice should only be used for short-lived operations without executing any Python code, such as copying into a Vec.

Examples

use pyo3::prelude::*;
use pyo3::exceptions::PyRuntimeError;
use pyo3::types::PyByteArray;

#[pyfunction]
fn a_valid_function(bytes: &PyByteArray) -> PyResult<()> {
    let section = {
        // SAFETY: We promise to not let the interpreter regain control
        // or invoke any PyO3 APIs while using the slice.
        let slice = unsafe { bytes.as_bytes() };

        // Copy only a section of `bytes` while avoiding
        // `to_vec` which copies the entire thing.
        let section = slice
            .get(6..11)
            .ok_or_else(|| PyRuntimeError::new_err("input is not long enough"))?;
        Vec::from(section)
    };

    // Now we can do things with `section` and call PyO3 APIs again.
    // ...

    Ok(())
}

Incorrect usage

The following bug function is unsound ⚠️

#[pyfunction]
fn bug(py: Python<'_>, bytes: &PyByteArray) {
    let slice = unsafe { bytes.as_bytes() };

    // This explicitly yields control back to the Python interpreter...
    // ...but it's not always this obvious. Many things do this implicitly.
    py.allow_threads(|| {
        // Python code could be mutating through its handle to `bytes`,
        // which makes reading it a data race, which is undefined behavior.
        println!("{:?}", slice[0]);
    });

    // Python code might have mutated it, so we can not rely on the slice
    // remaining valid. As such this is also undefined behavior.
    println!("{:?}", slice[0]);
}

pub unsafe fn as_bytes_mut(&self) -> &mut [u8]

Extracts a mutable slice of the ByteArray’s entire buffer.

Safety

Any other accesses of the bytearray’s buffer invalidate the slice. If it is used afterwards, the behavior is undefined. The safety requirements of PyByteArray::as_bytes apply to this function as well.

pub fn to_vec(&self) -> Vec<u8>

Copies the contents of the bytearray to a Rust vector.

Examples

let bytearray = PyByteArray::new(py, b"Hello World.");
let mut copied_message = bytearray.to_vec();
assert_eq!(b"Hello World.", copied_message.as_slice());

copied_message[11] = b'!';
assert_eq!(b"Hello World!", copied_message.as_slice());

pyo3::py_run!(py, bytearray, "assert bytearray == b'Hello World.'");

pub fn resize(&self, len: usize) -> PyResult<()>

Resizes the bytearray object to the new length len.

Note that this will invalidate any pointers obtained by PyByteArray::data, as well as any (unsafe) slices obtained from PyByteArray::as_bytes and PyByteArray::as_bytes_mut.

Methods from Deref<Target = PyAny>

pub fn is<T: AsPyPointer>(&self, other: &T) -> bool

Returns whether self and other point to the same object. To compare the equality of two objects (the == operator), use eq.

This is equivalent to the Python expression self is other.

pub fn hasattr<N>(&self, attr_name: N) -> PyResult<bool>where N: IntoPy<Py<PyString>>,

Determines whether this object has the given attribute.

This is equivalent to the Python expression hasattr(self, attr_name).

To avoid repeated temporary allocations of Python strings, the intern! macro can be used to intern attr_name.

Example: intern!ing the attribute name

#[pyfunction]
fn has_version(sys: &PyModule) -> PyResult<bool> {
    sys.hasattr(intern!(sys.py(), "version"))
}

pub fn getattr<N>(&self, attr_name: N) -> PyResult<&PyAny>where N: IntoPy<Py<PyString>>,

Retrieves an attribute value.

This is equivalent to the Python expression self.attr_name.

To avoid repeated temporary allocations of Python strings, the intern! macro can be used to intern attr_name.

Example: intern!ing the attribute name

#[pyfunction]
fn version(sys: &PyModule) -> PyResult<&PyAny> {
    sys.getattr(intern!(sys.py(), "version"))
}

pub fn setattr<N, V>(&self, attr_name: N, value: V) -> PyResult<()>where N: IntoPy<Py<PyString>>, V: ToPyObject,

Sets an attribute value.

This is equivalent to the Python expression self.attr_name = value.

To avoid repeated temporary allocations of Python strings, the intern! macro can be used to intern name.

Example: intern!ing the attribute name

#[pyfunction]
fn set_answer(ob: &PyAny) -> PyResult<()> {
    ob.setattr(intern!(ob.py(), "answer"), 42)
}

pub fn delattr<N>(&self, attr_name: N) -> PyResult<()>where N: IntoPy<Py<PyString>>,

Deletes an attribute.

This is equivalent to the Python statement del self.attr_name.

To avoid repeated temporary allocations of Python strings, the intern! macro can be used to intern attr_name.

pub fn compare<O>(&self, other: O) -> PyResult<Ordering>where O: ToPyObject,

Returns an Ordering between self and other.

This is equivalent to the following Python code:

if self == other:
    return Equal
elif a < b:
    return Less
elif a > b:
    return Greater
else:
    raise TypeError("PyAny::compare(): All comparisons returned false")

Examples

use pyo3::prelude::*;
use pyo3::types::PyFloat;
use std::cmp::Ordering;

Python::with_gil(|py| -> PyResult<()> {
    let a = PyFloat::new(py, 0_f64);
    let b = PyFloat::new(py, 42_f64);
    assert_eq!(a.compare(b)?, Ordering::Less);
    Ok(())
})?;

It will return PyErr for values that cannot be compared:

use pyo3::prelude::*;
use pyo3::types::{PyFloat, PyString};

Python::with_gil(|py| -> PyResult<()> {
    let a = PyFloat::new(py, 0_f64);
    let b = PyString::new(py, "zero");
    assert!(a.compare(b).is_err());
    Ok(())
})?;

pub fn rich_compare<O>( &self, other: O, compare_op: CompareOp ) -> PyResult<&PyAny>where O: ToPyObject,

Tests whether two Python objects obey a given CompareOp.

lt, le, eq, ne, gt and ge are the specialized versions of this function.

Depending on the value of compare_op, this is equivalent to one of the following Python expressions:

compare_op	Python expression
CompareOp::Eq	self == other
CompareOp::Ne	self != other
CompareOp::Lt	self < other
CompareOp::Le	self <= other
CompareOp::Gt	self > other
CompareOp::Ge	self >= other

Examples

use pyo3::class::basic::CompareOp;
use pyo3::prelude::*;
use pyo3::types::PyInt;

Python::with_gil(|py| -> PyResult<()> {
    let a: &PyInt = 0_u8.into_py(py).into_ref(py).downcast()?;
    let b: &PyInt = 42_u8.into_py(py).into_ref(py).downcast()?;
    assert!(a.rich_compare(b, CompareOp::Le)?.is_true()?);
    Ok(())
})?;

pub fn lt<O>(&self, other: O) -> PyResult<bool>where O: ToPyObject,

Tests whether this object is less than another.

This is equivalent to the Python expression self < other.

pub fn le<O>(&self, other: O) -> PyResult<bool>where O: ToPyObject,

Tests whether this object is less than or equal to another.

This is equivalent to the Python expression self <= other.

pub fn eq<O>(&self, other: O) -> PyResult<bool>where O: ToPyObject,

Tests whether this object is equal to another.

This is equivalent to the Python expression self == other.

pub fn ne<O>(&self, other: O) -> PyResult<bool>where O: ToPyObject,

Tests whether this object is not equal to another.

This is equivalent to the Python expression self != other.

pub fn gt<O>(&self, other: O) -> PyResult<bool>where O: ToPyObject,

Tests whether this object is greater than another.

This is equivalent to the Python expression self > other.

pub fn ge<O>(&self, other: O) -> PyResult<bool>where O: ToPyObject,

Tests whether this object is greater than or equal to another.

This is equivalent to the Python expression self >= other.

pub fn is_callable(&self) -> bool

Determines whether this object appears callable.

This is equivalent to Python’s callable() function.

Examples

use pyo3::prelude::*;

Python::with_gil(|py| -> PyResult<()> {
    let builtins = PyModule::import(py, "builtins")?;
    let print = builtins.getattr("print")?;
    assert!(print.is_callable());
    Ok(())
})?;

This is equivalent to the Python statement assert callable(print).

Note that unless an API needs to distinguish between callable and non-callable objects, there is no point in checking for callability. Instead, it is better to just do the call and handle potential exceptions.

pub fn call( &self, args: impl IntoPy<Py<PyTuple>>, kwargs: Option<&PyDict> ) -> PyResult<&PyAny>

Calls the object.

This is equivalent to the Python expression self(*args, **kwargs).

Examples

use pyo3::prelude::*;
use pyo3::types::PyDict;

const CODE: &str = r#"
def function(*args, **kwargs):
    assert args == ("hello",)
    assert kwargs == {"cruel": "world"}
    return "called with args and kwargs"
"#;

Python::with_gil(|py| {
    let module = PyModule::from_code(py, CODE, "", "")?;
    let fun = module.getattr("function")?;
    let args = ("hello",);
    let kwargs = PyDict::new(py);
    kwargs.set_item("cruel", "world")?;
    let result = fun.call(args, Some(kwargs))?;
    assert_eq!(result.extract::<&str>()?, "called with args and kwargs");
    Ok(())
})

pub fn call0(&self) -> PyResult<&PyAny>

Calls the object without arguments.

This is equivalent to the Python expression self().

Examples

use pyo3::prelude::*;

Python::with_gil(|py| -> PyResult<()> {
    let module = PyModule::import(py, "builtins")?;
    let help = module.getattr("help")?;
    help.call0()?;
    Ok(())
})?;

This is equivalent to the Python expression help().

pub fn call1(&self, args: impl IntoPy<Py<PyTuple>>) -> PyResult<&PyAny>

Calls the object with only positional arguments.

This is equivalent to the Python expression self(*args).

Examples

use pyo3::prelude::*;

const CODE: &str = r#"
def function(*args, **kwargs):
    assert args == ("hello",)
    assert kwargs == {}
    return "called with args"
"#;

Python::with_gil(|py| {
    let module = PyModule::from_code(py, CODE, "", "")?;
    let fun = module.getattr("function")?;
    let args = ("hello",);
    let result = fun.call1(args)?;
    assert_eq!(result.extract::<&str>()?, "called with args");
    Ok(())
})

pub fn call_method<N, A>( &self, name: N, args: A, kwargs: Option<&PyDict> ) -> PyResult<&PyAny>where N: IntoPy<Py<PyString>>, A: IntoPy<Py<PyTuple>>,

Calls a method on the object.

This is equivalent to the Python expression self.name(*args, **kwargs).

To avoid repeated temporary allocations of Python strings, the intern! macro can be used to intern name.

Examples

use pyo3::prelude::*;
use pyo3::types::PyDict;

const CODE: &str = r#"
class A:
    def method(self, *args, **kwargs):
        assert args == ("hello",)
        assert kwargs == {"cruel": "world"}
        return "called with args and kwargs"
a = A()
"#;

Python::with_gil(|py| {
    let module = PyModule::from_code(py, CODE, "", "")?;
    let instance = module.getattr("a")?;
    let args = ("hello",);
    let kwargs = PyDict::new(py);
    kwargs.set_item("cruel", "world")?;
    let result = instance.call_method("method", args, Some(kwargs))?;
    assert_eq!(result.extract::<&str>()?, "called with args and kwargs");
    Ok(())
})

pub fn call_method0<N>(&self, name: N) -> PyResult<&PyAny>where N: IntoPy<Py<PyString>>,

Calls a method on the object without arguments.

This is equivalent to the Python expression self.name().

To avoid repeated temporary allocations of Python strings, the intern! macro can be used to intern name.

Examples

use pyo3::prelude::*;

const CODE: &str = r#"
class A:
    def method(self, *args, **kwargs):
        assert args == ()
        assert kwargs == {}
        return "called with no arguments"
a = A()
"#;

Python::with_gil(|py| {
    let module = PyModule::from_code(py, CODE, "", "")?;
    let instance = module.getattr("a")?;
    let result = instance.call_method0("method")?;
    assert_eq!(result.extract::<&str>()?, "called with no arguments");
    Ok(())
})

pub fn call_method1<N, A>(&self, name: N, args: A) -> PyResult<&PyAny>where N: IntoPy<Py<PyString>>, A: IntoPy<Py<PyTuple>>,

Calls a method on the object with only positional arguments.

This is equivalent to the Python expression self.name(*args).

To avoid repeated temporary allocations of Python strings, the intern! macro can be used to intern name.

Examples

use pyo3::prelude::*;

const CODE: &str = r#"
class A:
    def method(self, *args, **kwargs):
        assert args == ("hello",)
        assert kwargs == {}
        return "called with args"
a = A()
"#;

Python::with_gil(|py| {
    let module = PyModule::from_code(py, CODE, "", "")?;
    let instance = module.getattr("a")?;
    let args = ("hello",);
    let result = instance.call_method1("method", args)?;
    assert_eq!(result.extract::<&str>()?, "called with args");
    Ok(())
})

pub fn is_true(&self) -> PyResult<bool>

Returns whether the object is considered to be true.

This is equivalent to the Python expression bool(self).

pub fn is_none(&self) -> bool

Returns whether the object is considered to be None.

This is equivalent to the Python expression self is None.

pub fn is_ellipsis(&self) -> bool

Returns whether the object is Ellipsis, e.g. ....

This is equivalent to the Python expression self is ....

pub fn is_empty(&self) -> PyResult<bool>

Returns true if the sequence or mapping has a length of 0.

This is equivalent to the Python expression len(self) == 0.

pub fn get_item<K>(&self, key: K) -> PyResult<&PyAny>where K: ToPyObject,

Gets an item from the collection.

This is equivalent to the Python expression self[key].

pub fn set_item<K, V>(&self, key: K, value: V) -> PyResult<()>where K: ToPyObject, V: ToPyObject,

Sets a collection item value.

This is equivalent to the Python expression self[key] = value.

pub fn del_item<K>(&self, key: K) -> PyResult<()>where K: ToPyObject,

Deletes an item from the collection.

This is equivalent to the Python expression del self[key].

pub fn iter(&self) -> PyResult<&PyIterator>

Takes an object and returns an iterator for it.

This is typically a new iterator but if the argument is an iterator, this returns itself.

pub fn get_type(&self) -> &PyType

Returns the Python type object for this object’s type.

pub fn get_type_ptr(&self) -> *mut PyTypeObject

Returns the Python type pointer for this object.

pub fn downcast<'p, T>(&'p self) -> Result<&'p T, PyDowncastError<'_>>where T: PyTryFrom<'p>,

Downcast this PyAny to a concrete Python type or pyclass.

Note that you can often avoid downcasting yourself by just specifying the desired type in function or method signatures. However, manual downcasting is sometimes necessary.

For extracting a Rust-only type, see PyAny::extract.

Example: Downcasting to a specific Python object

use pyo3::prelude::*;
use pyo3::types::{PyDict, PyList};

Python::with_gil(|py| {
    let dict = PyDict::new(py);
    assert!(dict.is_instance_of::<PyAny>());
    let any: &PyAny = dict.as_ref();

    assert!(any.downcast::<PyDict>().is_ok());
    assert!(any.downcast::<PyList>().is_err());
});

Example: Getting a reference to a pyclass

This is useful if you want to mutate a PyObject that might actually be a pyclass.

use pyo3::prelude::*;

#[pyclass]
struct Class {
    i: i32,
}

Python::with_gil(|py| {
    let class: &PyAny = Py::new(py, Class { i: 0 }).unwrap().into_ref(py);

    let class_cell: &PyCell<Class> = class.downcast()?;

    class_cell.borrow_mut().i += 1;

    // Alternatively you can get a `PyRefMut` directly
    let class_ref: PyRefMut<'_, Class> = class.extract()?;
    assert_eq!(class_ref.i, 1);
    Ok(())
})

pub fn downcast_exact<'p, T>(&'p self) -> Result<&'p T, PyDowncastError<'_>>where T: PyTryFrom<'p>,

Downcast this PyAny to a concrete Python type or pyclass (but not a subclass of it).

It is almost always better to use PyAny::downcast because it accounts for Python subtyping. Use this method only when you do not want to allow subtypes.

The advantage of this method over PyAny::downcast is that it is faster. The implementation of downcast_exact uses the equivalent of the Python expression type(self) is T, whereas downcast uses isinstance(self, T).

For extracting a Rust-only type, see PyAny::extract.

Example: Downcasting to a specific Python object but not a subtype

use pyo3::prelude::*;
use pyo3::types::{PyBool, PyLong};

Python::with_gil(|py| {
    let b = PyBool::new(py, true);
    assert!(b.is_instance_of::<PyBool>());
    let any: &PyAny = b.as_ref();

    // `bool` is a subtype of `int`, so `downcast` will accept a `bool` as an `int`
    // but `downcast_exact` will not.
    assert!(any.downcast::<PyLong>().is_ok());
    assert!(any.downcast_exact::<PyLong>().is_err());

    assert!(any.downcast_exact::<PyBool>().is_ok());
});

pub unsafe fn downcast_unchecked<'p, T>(&'p self) -> &'p Twhere T: PyTryFrom<'p>,

Converts this PyAny to a concrete Python type without checking validity.

Safety

Callers must ensure that the type is valid or risk type confusion.

pub fn extract<'a, D>(&'a self) -> PyResult<D>where D: FromPyObject<'a>,

Extracts some type from the Python object.

This is a wrapper function around FromPyObject::extract().

pub fn get_refcnt(&self) -> isize

Returns the reference count for the Python object.

pub fn repr(&self) -> PyResult<&PyString>

Computes the “repr” representation of self.

This is equivalent to the Python expression repr(self).

pub fn str(&self) -> PyResult<&PyString>

Computes the “str” representation of self.

This is equivalent to the Python expression str(self).

pub fn hash(&self) -> PyResult<isize>

Retrieves the hash code of self.

This is equivalent to the Python expression hash(self).

pub fn len(&self) -> PyResult<usize>

Returns the length of the sequence or mapping.

This is equivalent to the Python expression len(self).

pub fn dir(&self) -> &PyList

Returns the list of attributes of this object.

This is equivalent to the Python expression dir(self).

pub fn is_instance(&self, ty: &PyAny) -> PyResult<bool>

Checks whether this object is an instance of type ty.

This is equivalent to the Python expression isinstance(self, ty).

pub fn is_exact_instance(&self, ty: &PyAny) -> bool

Checks whether this object is an instance of exactly type ty (not a subclass).

This is equivalent to the Python expression type(self) is ty.

pub fn is_instance_of<T: PyTypeInfo>(&self) -> bool

Checks whether this object is an instance of type T.

This is equivalent to the Python expression isinstance(self, T), if the type T is known at compile time.

pub fn is_exact_instance_of<T: PyTypeInfo>(&self) -> bool

Checks whether this object is an instance of exactly type T.

This is equivalent to the Python expression type(self) is T, if the type T is known at compile time.

pub fn contains<V>(&self, value: V) -> PyResult<bool>where V: ToPyObject,

Determines if self contains value.

This is equivalent to the Python expression value in self.

pub fn py(&self) -> Python<'_>

Returns a GIL marker constrained to the lifetime of this type.

pub fn as_ptr(&self) -> *mut PyObject

Returns the raw FFI pointer represented by self.

Safety

Callers are responsible for ensuring that the pointer does not outlive self.

The reference is borrowed; callers should not decrease the reference count when they are finished with the pointer.

pub fn into_ptr(&self) -> *mut PyObject

Returns an owned raw FFI pointer represented by self.

Safety

The reference is owned; when finished the caller should either transfer ownership of the pointer or decrease the reference count (e.g. with pyo3::ffi::Py_DecRef).

pub fn py_super(&self) -> PyResult<&PySuper>

Return a proxy object that delegates method calls to a parent or sibling class of type.

This is equivalent to the Python expression super()

Trait Implementations

impl AsPyPointer for PyByteArray

fn as_ptr(&self) -> *mut PyObject

Gets the underlying FFI pointer, returns a borrowed pointer.

impl AsRef<PyAny> for PyByteArray

fn as_ref(&self) -> &PyAny

Converts this type into a shared reference of the (usually inferred) input type.

impl Debug for PyByteArray

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Deref for PyByteArray

type Target = PyAny

The resulting type after dereferencing.

fn deref(&self) -> &PyAny

Dereferences the value.

impl Display for PyByteArray

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'a> From<&'a PyByteArray> for &'a PyAny

fn from(ob: &'a PyByteArray) -> Self

Converts to this type from the input type.

impl From<&PyByteArray> for Py<PyByteArray>

fn from(other: &PyByteArray) -> Self

Converts to this type from the input type.

impl<'py> FromPyObject<'py> for &'py PyByteArray

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

Extracts Self from the source PyObject.

fn type_input() -> TypeInfo

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

impl IntoPy<Py<PyByteArray>> for &PyByteArray

fn into_py(self, py: Python<'_>) -> Py<PyByteArray>

Performs the conversion.

fn type_output() -> TypeInfo

Extracts the type hint information for this type when it appears as a return value.

impl PyNativeType for PyByteArray

fn py(&self) -> Python<'_>

Returns a GIL marker constrained to the lifetime of this type.

unsafe fn unchecked_downcast(obj: &PyAny) -> &Self

Cast &PyAny to &Self without no type checking.

impl PyTypeInfo for PyByteArray

type AsRefTarget = PyByteArray

Utility type to make Py::as_ref work.

const NAME: &'static str = _

Class name.

const MODULE: Option<&'static str> = _

Module name, if any.

fn type_object_raw(py: Python<'_>) -> *mut PyTypeObject

Returns the PyTypeObject instance for this type.

fn is_type_of(ptr: &PyAny) -> bool

Checks if object is an instance of this type or a subclass of this type.

fn type_object(py: Python<'_>) -> &PyType

Returns the safe abstraction over the type object.

fn is_exact_type_of(object: &PyAny) -> bool

Checks if object is an instance of this type.

impl ToPyObject for PyByteArray

fn to_object(&self, py: Python<'_>) -> PyObject

Converts self into a Python object.