Struct ExternalPtrMut 

pub struct ExternalPtrMut<'a, T: TypedExternal + ?Sized> {
    value: Exclusive<'a, T>,
    owner: &'a SEXP,
    _main_thread: PhantomData<*mut ()>,
}

An exclusive borrow of a Rust value together with its R object.

ExternalPtr::borrow_mut makes one, and a #[miniextendr] function or method takes one as a parameter (or as self: ExternalPtrMut<'_, Self>) when it needs the R object as well as the value, like ExternalPtrRef. Dereferencing gives mutable access to the Rust fields; the sidecar setters use the R object. There is no consuming API.

The view holds an exclusive borrow of the value’s RefCell for its whole lifetime: any other borrow of the value meanwhile raises the R error of class miniextendr_borrow_conflict. Pass it on without moving it with rb_mut, or as a shared view with rb.

A view borrows its handle for as long as it lives:

use miniextendr_api::{ExternalPtr, ExternalPtrMut, ExternalPtrRef, TypedExternal};
fn overlap<T: TypedExternal>(owner: &mut ExternalPtr<T>) {
    let mut first = owner.borrow_mut();
    let second = owner.borrow();
    let _ = (&mut *first, second);
}

A reborrow ends before the view is used again:

use miniextendr_api::{ExternalPtrMut, TypedExternal};
fn twice<T: TypedExternal>(view: &mut ExternalPtrMut<'_, T>) {
    let first = view.rb_mut();
    let second = view.rb_mut();
    let _ = (first, second);
}

Fields

value: Exclusive<'a, T>

owner: &'a SEXP

_main_thread: PhantomData<*mut ()>

Implementations

impl<'a, T: TypedExternal + ?Sized> ExternalPtrMut<'a, T>

pub(super) fn from_guard(owner: &'a SEXP, guard: RefMut<'a, T>) -> Self

Hold guard, an exclusive borrow of the value of the R object owner.

pub fn rb(&self) -> ExternalPtrRef<'_, T>

A shared view of the same value, for as long as this view isn’t used mutably.

pub fn rb_mut(&mut self) -> ExternalPtrMut<'_, T>

An exclusive view of the same value for a shorter lifetime, to pass on without moving this one.

pub fn as_sexp(this: &Self) -> SEXP

The R object (EXTPTRSXP) holding the value.

An associated function, ExternalPtrMut::as_sexp(&view), so that it doesn’t hide a method of T of the same name.

impl<'a, T: TypedExternal> ExternalPtrMut<'a, T>

#[doc(hidden)]

pub unsafe fn from_raw_parts(owner: &'a SEXP, cell: *const RefCell<T>) -> Self

Borrow a receiver after its type and argument aliases have been checked.

Safety

R’s main thread; cell must point to the live RefCell<T> owned by owner, whose initialized sidecar slots use T’s layout. Its SEXP must stay rooted for 'a; the slot reference alone does not root it. The cell must remain valid for 'a.

Trait Implementations

impl<T: TypedExternal + ?Sized + Debug> Debug for ExternalPtrMut<'_, T>

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

Formats the value using the given formatter.

impl<T: TypedExternal + ?Sized> Deref for ExternalPtrMut<'_, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T: TypedExternal + ?Sized> DerefMut for ExternalPtrMut<'_, T>

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<T: TypedExternal + ?Sized + Display> Display for ExternalPtrMut<'_, T>

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

Formats the value using the given formatter.

impl<T: TypedExternal + ?Sized> Owner for ExternalPtrMut<'_, T>

impl<T: TypedExternal + ?Sized> SidecarOwner<T> for ExternalPtrMut<'_, T>

fn __mx_read(&self) -> SidecarRead<'_, T>

The value, borrowed shared, with its R object; or, for a Saved handle, the restored pointer alone.

impl<T: TypedExternal + ?Sized> SidecarOwnerMut<T> for ExternalPtrMut<'_, T>

fn __mx_write(&mut self) -> ExternalPtrMut<'_, T>

The value, borrowed exclusively, with its R object.

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.