Struct ExternalPtrRef 

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

A shared borrow of a Rust value together with its R object.

ExternalPtr::borrow makes one, and a #[miniextendr] function or method takes one as a parameter (or as self: ExternalPtrRef<'_, Self>) when it needs the R object as well as the value: the sidecar accessors, the object’s identity (ExternalPtrRef::as_sexp). A body that needs only the value takes &T.

The view holds a shared borrow of the value’s RefCell for its whole lifetime: a method of the same object that needs it mutably, a &mut T argument holding it, or ExternalPtr::borrow_mut meanwhile raises the R error of class miniextendr_borrow_conflict. It never owns or consumes the value, can represent ordinary Any storage or erased trait-ABI storage, and cannot cross threads. Pass it on without moving it with rb.

A borrowed handle cannot outlive its owner:

use miniextendr_api::{ExternalPtr, ExternalPtrRef, TypedExternal};
fn escape<T: TypedExternal>(owner: ExternalPtr<T>) -> ExternalPtrRef<'static, T> {
    owner.borrow()
}

Fields

value: Shared<'a, T>

owner: &'a SEXP

_main_thread: PhantomData<*mut ()>

Implementations

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

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

Hold guard, a borrow of the value of the R object owner.

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

A shared view of the same value for a shorter lifetime, to pass on without moving this one. The value stays borrowed until this view drops.

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

The R object (EXTPTRSXP) holding the value.

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

impl<'a, T: TypedExternal> ExternalPtrRef<'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 ExternalPtrRef<'_, T>

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

Formats the value using the given formatter.

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

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

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

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

Formats the value using the given formatter.

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

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

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

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

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.