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<h1 class='fqn'><span class='in-band'>Struct <a href='../index.html'>core</a>::<wbr><a href='index.html'>cell</a>::<wbr><a class="struct" href=''>Ref</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'>
<a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
[<span class='inner'>−</span>]
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</span><a class='srclink' href='../../src/core/cell.rs.html#879-882' title='goto source code'>[src]</a></span></h1>
<pre class='rust struct'>pub struct Ref<'b, T: ?<a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + 'b> { /* fields omitted */ }</pre><div class='docblock'><p>Wraps a borrowed reference to a value in a <code>RefCell</code> box.
A wrapper type for an immutably borrowed value from a <code>RefCell<T></code>.</p>
<p>See the <a href="index.html">module-level documentation</a> for more.</p>
</div><h2 id='methods'>Methods</h2><h3 class='impl'><span class='in-band'><code>impl<'b, T: ?<a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>> <a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, T></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/cell.rs.html#894-940' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.clone' class="method"><span id='clone.v' class='invisible'><code>fn <a href='#method.clone' class='fnname'>clone</a>(orig: &<a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, T>) -> <a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, T></code><div class='since' title='Stable since Rust version 1.15.0'>1.15.0</div></span></h4>
<div class='docblock'><p>Copies a <code>Ref</code>.</p>
<p>The <code>RefCell</code> is already immutably borrowed, so this cannot fail.</p>
<p>This is an associated function that needs to be used as
<code>Ref::clone(...)</code>. A <code>Clone</code> implementation or a method would interfere
with the widespread use of <code>r.borrow().clone()</code> to clone the contents of
a <code>RefCell</code>.</p>
</div><h4 id='method.map' class="method"><span id='map.v' class='invisible'><code>fn <a href='#method.map' class='fnname'>map</a><U: ?<a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, F>(orig: <a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, T>, f: F) -> <a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, U> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../core/ops/trait.FnOnce.html" title="trait core::ops::FnOnce">FnOnce</a>(&T) -> &U, </span></code><div class='since' title='Stable since Rust version 1.8.0'>1.8.0</div></span></h4>
<div class='docblock'><p>Make a new <code>Ref</code> for a component of the borrowed data.</p>
<p>The <code>RefCell</code> is already immutably borrowed, so this cannot fail.</p>
<p>This is an associated function that needs to be used as <code>Ref::map(...)</code>.
A method would interfere with methods of the same name on the contents
of a <code>RefCell</code> used through <code>Deref</code>.</p>
<h1 id='example' class='section-header'><a href='#example'>Example</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">cell</span>::{<span class="ident">RefCell</span>, <span class="ident">Ref</span>};
<span class="kw">let</span> <span class="ident">c</span> <span class="op">=</span> <span class="ident">RefCell</span>::<span class="ident">new</span>((<span class="number">5</span>, <span class="string">'b'</span>));
<span class="kw">let</span> <span class="ident">b1</span>: <span class="ident">Ref</span><span class="op"><</span>(<span class="ident">u32</span>, <span class="ident">char</span>)<span class="op">></span> <span class="op">=</span> <span class="ident">c</span>.<span class="ident">borrow</span>();
<span class="kw">let</span> <span class="ident">b2</span>: <span class="ident">Ref</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="ident">Ref</span>::<span class="ident">map</span>(<span class="ident">b1</span>, <span class="op">|</span><span class="ident">t</span><span class="op">|</span> <span class="kw-2">&</span><span class="ident">t</span>.<span class="number">0</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">b2</span>, <span class="number">5</span>)<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Acell%3A%3A%7BRefCell%2C%20Ref%7D%3B%0A%0Alet%20c%20%3D%20RefCell%3A%3Anew((5%2C%20'b'))%3B%0Alet%20b1%3A%20Ref%3C(u32%2C%20char)%3E%20%3D%20c.borrow()%3B%0Alet%20b2%3A%20Ref%3Cu32%3E%20%3D%20Ref%3A%3Amap(b1%2C%20%7Ct%7C%20%26t.0)%3B%0Aassert_eq!(*b2%2C%205)%0A%7D">Run</a></pre>
</div></div><h2 id='implementations'>Trait Implementations</h2><h3 class='impl'><span class='in-band'><code>impl<'b, T: ?<a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>> <a class="trait" href="../../core/ops/trait.Deref.html" title="trait core::ops::Deref">Deref</a> for <a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, T></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/cell.rs.html#885-892' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='associatedtype.Target' class="type"><span id='Target.t' class='invisible'><code>type <a href='../../core/ops/trait.Deref.html#associatedtype.Target' class="type">Target</a> = T</code></span></h4>
<div class='docblock'><p>The resulting type after dereferencing</p>
</div><h4 id='method.deref' class="method"><span id='deref.v' class='invisible'><code>fn <a href='../../core/ops/trait.Deref.html#tymethod.deref' class='fnname'>deref</a>(&self) -> &T</code></span></h4>
<div class='docblock'><p>The method called to dereference a value</p>
</div></div><h3 class='impl'><span class='in-band'><code>impl<'b, T: ?<a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="../../core/marker/trait.Unsize.html" title="trait core::marker::Unsize">Unsize</a><U>, U: ?<a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>> <a class="trait" href="../../core/ops/trait.CoerceUnsized.html" title="trait core::ops::CoerceUnsized">CoerceUnsized</a><<a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, U>> for <a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, T></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/cell.rs.html#943' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'></div><h3 class='impl'><span class='in-band'><code>impl<'b, T: ?<a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a> + <a class="trait" href="../../core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a>> <a class="trait" href="../../core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="struct" href="../../core/cell/struct.Ref.html" title="struct core::cell::Ref">Ref</a><'b, T></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/core/fmt/mod.rs.html#1699-1703' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><code>fn <a href='../../core/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, f: &mut <a class="struct" href="../../core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -> <a class="type" href="../../core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></code></span></h4>
<div class='docblock'><p>Formats the value using the given formatter.</p>
</div></div></section>
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