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<ul class="chapter"><li class="affix"><a href="README.html">Introduction</a></li><li><a href="meet-safe-and-unsafe.html"><strong>1.</strong> Meet Safe and Unsafe</a></li><li><ul class="section"><li><a href="safe-unsafe-meaning.html"><strong>1.1.</strong> How Safe and Unsafe Interact</a></li><li><a href="working-with-unsafe.html"><strong>1.2.</strong> Working with Unsafe</a></li></ul></li><li><a href="data.html"><strong>2.</strong> Data Layout</a></li><li><ul class="section"><li><a href="repr-rust.html"><strong>2.1.</strong> repr(Rust)</a></li><li><a href="exotic-sizes.html"><strong>2.2.</strong> Exotically Sized Types</a></li><li><a href="other-reprs.html"><strong>2.3.</strong> Other reprs</a></li></ul></li><li><a href="ownership.html"><strong>3.</strong> Ownership</a></li><li><ul class="section"><li><a href="references.html"><strong>3.1.</strong> References</a></li><li><a href="lifetimes.html"><strong>3.2.</strong> Lifetimes</a></li><li><a href="lifetime-mismatch.html"><strong>3.3.</strong> Limits of Lifetimes</a></li><li><a href="lifetime-elision.html"><strong>3.4.</strong> Lifetime Elision</a></li><li><a href="unbounded-lifetimes.html"><strong>3.5.</strong> Unbounded Lifetimes</a></li><li><a href="hrtb.html"><strong>3.6.</strong> Higher-Rank Trait Bounds</a></li><li><a href="subtyping.html"><strong>3.7.</strong> Subtyping and Variance</a></li><li><a href="dropck.html"><strong>3.8.</strong> Drop Check</a></li><li><a href="phantom-data.html"><strong>3.9.</strong> PhantomData</a></li><li><a href="borrow-splitting.html"><strong>3.10.</strong> Splitting Borrows</a></li></ul></li><li><a href="conversions.html"><strong>4.</strong> Type Conversions</a></li><li><ul class="section"><li><a href="coercions.html"><strong>4.1.</strong> Coercions</a></li><li><a href="dot-operator.html"><strong>4.2.</strong> The Dot Operator</a></li><li><a href="casts.html"><strong>4.3.</strong> Casts</a></li><li><a href="transmutes.html"><strong>4.4.</strong> Transmutes</a></li></ul></li><li><a href="uninitialized.html"><strong>5.</strong> Uninitialized Memory</a></li><li><ul class="section"><li><a href="checked-uninit.html"><strong>5.1.</strong> Checked</a></li><li><a href="drop-flags.html"><strong>5.2.</strong> Drop Flags</a></li><li><a href="unchecked-uninit.html"><strong>5.3.</strong> Unchecked</a></li></ul></li><li><a href="obrm.html"><strong>6.</strong> Ownership Based Resource Management</a></li><li><ul class="section"><li><a href="constructors.html"><strong>6.1.</strong> Constructors</a></li><li><a href="destructors.html"><strong>6.2.</strong> Destructors</a></li><li><a href="leaking.html"><strong>6.3.</strong> Leaking</a></li></ul></li><li><a href="unwinding.html"><strong>7.</strong> Unwinding</a></li><li><ul class="section"><li><a href="exception-safety.html"><strong>7.1.</strong> Exception Safety</a></li><li><a href="poisoning.html"><strong>7.2.</strong> Poisoning</a></li></ul></li><li><a href="concurrency.html"><strong>8.</strong> Concurrency</a></li><li><ul class="section"><li><a href="races.html"><strong>8.1.</strong> Races</a></li><li><a href="send-and-sync.html"><strong>8.2.</strong> Send and Sync</a></li><li><a href="atomics.html"><strong>8.3.</strong> Atomics</a></li></ul></li><li><a href="vec.html"><strong>9.</strong> Implementing Vec</a></li><li><ul class="section"><li><a href="vec-layout.html"><strong>9.1.</strong> Layout</a></li><li><a href="vec-alloc.html"><strong>9.2.</strong> Allocating</a></li><li><a href="vec-push-pop.html"><strong>9.3.</strong> Push and Pop</a></li><li><a href="vec-dealloc.html"><strong>9.4.</strong> Deallocating</a></li><li><a href="vec-deref.html" class="active"><strong>9.5.</strong> Deref</a></li><li><a href="vec-insert-remove.html"><strong>9.6.</strong> Insert and Remove</a></li><li><a href="vec-into-iter.html"><strong>9.7.</strong> IntoIter</a></li><li><a href="vec-raw.html"><strong>9.8.</strong> RawVec</a></li><li><a href="vec-drain.html"><strong>9.9.</strong> Drain</a></li><li><a href="vec-zsts.html"><strong>9.10.</strong> Handling Zero-Sized Types</a></li><li><a href="vec-final.html"><strong>9.11.</strong> Final Code</a></li></ul></li><li><a href="arc-and-mutex.html"><strong>10.</strong> Implementing Arc and Mutex</a></li><li><a href="ffi.html"><strong>11.</strong> FFI</a></li></ul>
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<a class="header" href="vec-deref.html#deref" id="deref"><h1>Deref</h1></a>
<p>Alright! We've got a decent minimal stack implemented. We can push, we can
pop, and we can clean up after ourselves. However there's a whole mess of
functionality we'd reasonably want. In particular, we have a proper array, but
none of the slice functionality. That's actually pretty easy to solve: we can
implement <code>Deref<Target=[T]></code>. This will magically make our Vec coerce to, and
behave like, a slice in all sorts of conditions.</p>
<p>All we need is <code>slice::from_raw_parts</code>. It will correctly handle empty slices
for us. Later once we set up zero-sized type support it will also Just Work
for those too.</p>
<pre><code class="language-rust ignore">use std::ops::Deref;
impl<T> Deref for Vec<T> {
type Target = [T];
fn deref(&self) -> &[T] {
unsafe {
::std::slice::from_raw_parts(self.ptr.as_ptr(), self.len)
}
}
}
</code></pre>
<p>And let's do DerefMut too:</p>
<pre><code class="language-rust ignore">use std::ops::DerefMut;
impl<T> DerefMut for Vec<T> {
fn deref_mut(&mut self) -> &mut [T] {
unsafe {
::std::slice::from_raw_parts_mut(self.ptr.as_ptr(), self.len)
}
}
}
</code></pre>
<p>Now we have <code>len</code>, <code>first</code>, <code>last</code>, indexing, slicing, sorting, <code>iter</code>,
<code>iter_mut</code>, and all other sorts of bells and whistles provided by slice. Sweet!</p>
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