Struct kobold::internal::In

#[repr(transparent)]
pub struct In<'a, T>(_);

Uninitialized stable pointer to T.

Used for the initialize-in-place strategy employed by the View::build method.

Implementations

impl<'a, T> In<'a, T>

pub unsafe fn cast<U>(self) -> In<'a, U>

Cast this pointer from In<T> to In<U>.

Safety

Caller needs to guarantee safety as per usual rules of pointer casting, namely:

1. T and U must have the same size.
2. T and U must have the same memory layout.

pub fn in_place<F>(self, f: F) -> Out<'a, T>where F: FnOnce(*mut T) -> Out<'a, T>,

Build this T in-place using a raw pointer

Safety

This method itself is safe since just obtaining a raw pointer by itself is also safe, it does however require unsafe code to construct Out<T> inside the closure f.

use kobold::internal::{In, Out};
use kobold::init;

struct Foo {
    int: u32,
    float: f64,
}

fn build_in(p: In<Foo>) -> Out<Foo> {
    let out = p.in_place(|p| unsafe {
        // Initialize fields of `Foo`
        init!(p.int = 42);
        init!(p.float = 3.14);

        // Both fields have been initialized
        Out::from_raw(p)
    });

    assert_eq!(out.int, 42);
    assert_eq!(out.float, 3.14);

    out
}

pub unsafe fn raw<F>(raw: *mut T, f: F) -> Out<'a, T>where F: FnOnce(In<'_, T>) -> Out<'_, T>,

Initialize raw pointer raw using a builder closure f.

Safety

Caller must guarantee that raw is a stable pointer for the entire life of T.

If raw has already been initialized this can cause a memory leak, which is safe but undesirable.

pub fn pinned<F>(pin: Pin<&'a mut MaybeUninit<T>>, f: F) -> Out<'a, T>where F: FnOnce(In<'_, T>) -> Out<'_, T>,

Initialize a pinned uninitialized data using a builder closure f.

Safety

This method is safe, it can however leak memory if pin has already been initialized.

pub fn replace<F>(at: &mut T, f: F) -> Twhere F: FnOnce(In<'_, T>) -> Out<'_, T>,

Replace previous value of T with a new value produced by a builder closure f. Returns the old value.

pub fn put(self, val: T) -> Out<'a, T>

Initialize this pointer with some value of T.