#[feature(managed_boxes)];
#[deriving(Clone)]
struct Foo;
impl Drop for Foo {
fn drop(&mut self) { }
}
fn main() {
let x = ~Foo;
let y = @Foo;
let _z = Foo;
let z = &_z;
// needs a clone since just `a = x` would be a move
let a: ~Foo = x.clone();
// just copies the pointer (and bumps the refcount)
let b: @Foo = y;
// copies the pointer
let c = z;
// *NOT* allowed; would be a move out of a borrowed pointer, which
is not allowed since borrowed
// pointers don't have ownership.
// let d = *z;
}
On Tue, Nov 12, 2013 at 8:52 AM, spir <[email protected]> wrote:
> Hello,
>
> The ref manual speaks of copying pointers
> [http://static.rust-lang.org/doc/0.8/rust.html#pointer-types]:
>
> <<
> Managed pointers (@)
> These point to managed heap allocations (or "boxes") in the task-local,
> managed heap. Managed pointers are written @content, for example @int means
> a managed pointer to a managed box containing an integer. Copying a managed
> pointer is a "shallow" operation: it involves only copying the pointer
> itself (as well as any reference-count or GC-barriers required by the
> managed heap). Dropping a managed pointer does not necessarily release the
> box it points to; the lifecycles of managed boxes are subject to an
> unspecified garbage collection algorithm.
>
> Owning pointers (~)
> These point to owned heap allocations (or "boxes") in the shared,
> inter-task heap. Each owned box has a single owning pointer; pointer and
> pointee retain a 1:1 relationship at all times. Owning pointers are written
> ~content, for example ~int means an owning pointer to an owned box
> containing an integer. Copying an owned box is a "deep" operation: it
> involves allocating a new owned box and copying the contents of the old box
> into the new box. Releasing an owning pointer immediately releases its
> corresponding owned box.
>
> Borrowed pointers (&)
> These point to memory owned by some other value. Borrowed pointers arise
> by (automatic) conversion from owning pointers, managed pointers, or by
> applying the borrowing operator & to some other value, including lvalues,
> rvalues or temporaries. Borrowed pointers are written &content, or in some
> cases &f/content for some lifetime-variable f, for example &int means a
> borrowed pointer to an integer. Copying a borrowed pointer is a "shallow"
> operation: it involves only copying the pointer itself. Releasing a borrowed
> pointer typically has no effect on the value it points to, with the
> exception of temporary values, which are released when the last borrowed
> pointer to them is released.
>>>
>>>
>
> But what is the syntax to do that? I always get errors related to moving,
> which i don' twant to do. In particular, how does one establish or modify
> link list links?
>
> Denis
> _______________________________________________
> Rust-dev mailing list
> [email protected]
> https://mail.mozilla.org/listinfo/rust-dev
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