Struct GILOnceCell 

pub(crate) struct GILOnceCell<T> {
    once: Once,
    data: UnsafeCell<MaybeUninit<T>>,
    _marker: PhantomData<T>,
}

👎Deprecated since 0.26.0:

Now internal only, to be removed after https://github.com/PyO3/pyo3/pull/5341

Fields

once: Once

👎Deprecated since 0.26.0:

Now internal only, to be removed after https://github.com/PyO3/pyo3/pull/5341

data: UnsafeCell<MaybeUninit<T>>

👎Deprecated since 0.26.0:

Now internal only, to be removed after https://github.com/PyO3/pyo3/pull/5341

_marker: PhantomData<T>

👎Deprecated since 0.26.0:

Now internal only, to be removed after https://github.com/PyO3/pyo3/pull/5341

(Copied from std::sync::OnceLock)

PhantomData to make sure dropck understands we’re dropping T in our Drop impl.

#![allow(deprecated)]
use pyo3::Python;
use pyo3::sync::GILOnceCell;

struct A<'a>(#[allow(dead_code)] &'a str);

impl<'a> Drop for A<'a> {
    fn drop(&mut self) {}
}

let cell = GILOnceCell::new();
{
    let s = String::new();
    let _ = Python::attach(|py| cell.set(py,A(&s)));
}

Implementations

impl<T> GILOnceCell<T>

pub const fn new() -> Self

Create a GILOnceCell which does not yet contain a value.

pub fn get(&self, _py: Python<'_>) -> Option<&T>

Get a reference to the contained value, or None if the cell has not yet been written.

pub fn get_or_try_init<F, E>(&self, py: Python<'_>, f: F) -> Result<&T, E>

where F: FnOnce() -> Result<T, E>,

Like get_or_init, but accepts a fallible initialization function. If it fails, the cell is left uninitialized.

See the type-level documentation for detail on re-entrancy and concurrent initialization.

fn init<F, E>(&self, py: Python<'_>, f: F) -> Result<&T, E>

where F: FnOnce() -> Result<T, E>,

pub fn set(&self, _py: Python<'_>, value: T) -> Result<(), T>

Set the value in the cell.

If the cell has already been written, Err(value) will be returned containing the new value which was not written.

Trait Implementations

impl<T> Default for GILOnceCell<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T> Drop for GILOnceCell<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T: Send> Send for GILOnceCell<T>

impl<T: Send + Sync> Sync for GILOnceCell<T>