add draft on Tree Borrows

[web.git] / personal / _posts / 2018-04-05-a-formal-look-at-pinning.md

diff --git a/personal/_posts/2018-04-05-a-formal-look-at-pinning.md b/personal/_posts/2018-04-05-a-formal-look-at-pinning.md
index 121de4b1f3401f8feede4bcd3402d942d6b2657c..5e51e7c747dbc01a0307a5f343b28e21cd27997c 100644 (file)
--- a/personal/_posts/2018-04-05-a-formal-look-at-pinning.md
+++ b/personal/_posts/2018-04-05-a-formal-look-at-pinning.md
@@ -44,7 +44,7 @@ The core piece of the pinning API is a new reference type `Pin<'a, T>` that guar
 Crucially, **pinning does not provide immovable types**!
 Data is only pinned after a `Pin<T>` pointing to it has been created; it can be moved freely before that happens.
 
-The [corresponding RFC](https://github.com/rust-lang/rfcs/blob/master/text/2349-pin.md) explains the entirey new API surface in quite some detail: [`Pin`](https://doc.rust-lang.org/nightly/std/mem/struct.Pin.html), [`PinBox`](https://doc.rust-lang.org/nightly/std/boxed/struct.PinBox.html) and the [`Unpin`](https://doc.rust-lang.org/nightly/std/marker/trait.Unpin.html) marker trait.
+The [corresponding RFC](https://github.com/rust-lang/rfcs/blob/master/text/2349-pin.md) explains the entirey new API surface in quite some detail: [`Pin`](https://doc.rust-lang.org/1.27.0/std/mem/struct.Pin.html), [`PinBox`](https://doc.rust-lang.org/1.27.0/std/boxed/struct.PinBox.html) and the [`Unpin`](https://doc.rust-lang.org/1.27.0/std/marker/trait.Unpin.html) marker trait.
 I will not repeat that here but only show one example of how to use `Pin` references and exploit their guarantees:
 {% highlight rust %}
 #![feature(pin, arbitrary_self_types, optin_builtin_traits)]
@@ -68,11 +68,11 @@ impl SelfReferential {
     fn init(mut self: Pin<SelfReferential>) {
         let this : &mut SelfReferential = unsafe { Pin::get_mut(&mut self) };
         // Set up self_ref to point to this.data.
-        this.self_ref = &mut this.data as *const i32;
+        this.self_ref = &this.data as *const i32;
     }
 
-    fn read_ref(mut self: Pin<SelfReferential>) -> Option<i32> {
-        let this : &mut SelfReferential = unsafe { Pin::get_mut(&mut self) };
+    fn read_ref(self: Pin<SelfReferential>) -> Option<i32> {
+        let this : &SelfReferential = &*self;
         // Dereference self_ref if it is non-NULL.
         if this.self_ref == ptr::null() {
             None