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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Provides a macro to simplify operator overloading."><title>overload - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../static.files/rustdoc-ac92e1bbe349e143.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="overload" data-themes="" data-resource-suffix="" data-rustdoc-version="1.76.0 (07dca489a 2024-02-04)" data-channel="1.76.0" data-search-js="search-2b6ce74ff89ae146.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../static.files/storage-f2adc0d6ca4d09fb.js"></script><script defer src="../crates.js"></script><script defer src="../static.files/main-305769736d49e732.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-feafe1bb7466e4bd.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc mod crate"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../overload/index.html">overload</a><span class="version">0.1.1</span></h2></div><div class="sidebar-elems"><ul class="block">
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<li><a id="all-types" href="all.html">All Items</a></li></ul><section><ul class="block"><li><a href="#macros">Macros</a></li></ul></section></div></nav><div class="sidebar-resizer"></div>
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<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../overload/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Crate <a class="mod" href="#">overload</a><button id="copy-path" title="Copy item path to clipboard"><img src="../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../src/overload/lib.rs.html#1-257">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>−</span>]</button></span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Provides a macro to simplify operator overloading.</p>
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<p>To use, include the following:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">extern crate </span>overload;
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<span class="kw">use </span>overload::overload;
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<span class="kw">use </span>std::ops; <span class="comment">// <- don't forget this or you'll get nasty errors</span></code></pre></div>
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<h2 id="introduction"><a href="#introduction">Introduction</a></h2>
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<p>Suppose we have the following <code>struct</code> definition:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="attr">#[derive(PartialEq, Debug)]
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</span><span class="kw">struct </span>Val {
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v: i32
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}</code></pre></div>
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<p>We can overload the addition of <code>Val</code>s like so:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">overload!</span>((a: Val) + (b: Val) -> Val { Val { v: a.v + b.v } });</code></pre></div>
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<p>The macro call above generates the following code:</p>
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<div class="example-wrap ignore"><a href="#" class="tooltip" title="This example is not tested">ⓘ</a><pre class="rust rust-example-rendered"><code><span class="kw">impl </span>ops::Add<Val> <span class="kw">for </span>Val {
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<span class="kw">type </span>Output = Val;
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<span class="kw">fn </span>add(<span class="self">self</span>, b: Val) -> <span class="self">Self</span>::Output {
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<span class="kw">let </span>a = <span class="self">self</span>;
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Val { v: a.v + b.v }
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}
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}</code></pre></div>
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<p>We are now able to add <code>Val</code>s:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">assert_eq!</span>(Val{v:<span class="number">3</span>} + Val{v:<span class="number">5</span>}, Val{v:<span class="number">8</span>});</code></pre></div>
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<h2 id="owned-and-borrowed-types"><a href="#owned-and-borrowed-types">Owned and borrowed types</a></h2>
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<p>If we also wanted to overload addition for the borrowed type <code>&Val</code> we could write:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">overload!</span>((a: <span class="kw-2">&</span>Val) + (b: <span class="kw-2">&</span>Val) -> Val { Val { v: a.v + b.v } });</code></pre></div>
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<p>We might also want to overload addition between the owned and borrowed types:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">overload!</span>((a: Val) + (b: <span class="kw-2">&</span>Val) -> Val { Val { v: a.v + b.v } });
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<span class="macro">overload!</span>((a: <span class="kw-2">&</span>Val) + (b: Val) -> Val { Val { v: a.v + b.v } });</code></pre></div>
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<p>Let’s see how we can write these combinations more concisely.</p>
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<p>We can include a <code>?</code> in front of a type to indicate that it should stand in for both the owned and borrowed type.</p>
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<p>To overload addition for all four combinations between <code>Val</code> and <code>&Val</code> we can therefore simply include a <code>?</code> in front of both types:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">overload!</span>((a: <span class="question-mark">?</span>Val) + (b: <span class="question-mark">?</span>Val) -> Val { Val { v: a.v + b.v } });</code></pre></div>
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<p>The macro call above generates the following code:</p>
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<div class="example-wrap ignore"><a href="#" class="tooltip" title="This example is not tested">ⓘ</a><pre class="rust rust-example-rendered"><code><span class="kw">impl </span>ops::Add<Val> <span class="kw">for </span>Val {
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<span class="kw">type </span>Output = Val;
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<span class="kw">fn </span>add(<span class="self">self</span>, b: Val) -> <span class="self">Self</span>::Output {
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<span class="kw">let </span>a = <span class="self">self</span>;
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Val { v: a.v + b.v }
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}
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}
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<span class="kw">impl </span>ops::Add<<span class="kw-2">&</span>Val> <span class="kw">for </span>Val {
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<span class="kw">type </span>Output = Val;
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<span class="kw">fn </span>add(<span class="self">self</span>, b: <span class="kw-2">&</span>Val) -> <span class="self">Self</span>::Output {
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<span class="kw">let </span>a = <span class="self">self</span>;
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Val { v: a.v + b.v }
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}
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}
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<span class="kw">impl </span>ops::Add<Val> <span class="kw">for </span><span class="kw-2">&</span>Val {
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<span class="kw">type </span>Output = Val;
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<span class="kw">fn </span>add(<span class="self">self</span>, b: Val) -> <span class="self">Self</span>::Output {
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<span class="kw">let </span>a = <span class="self">self</span>;
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Val { v: a.v + b.v }
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}
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}
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<span class="kw">impl </span>ops::Add<<span class="kw-2">&</span>Val> <span class="kw">for </span><span class="kw-2">&</span>Val {
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<span class="kw">type </span>Output = Val;
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<span class="kw">fn </span>add(<span class="self">self</span>, b: <span class="kw-2">&</span>Val) -> <span class="self">Self</span>::Output {
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<span class="kw">let </span>a = <span class="self">self</span>;
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Val { v: a.v + b.v }
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}
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}</code></pre></div>
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<p>We are now able to add <code>Val</code>s and <code>&Val</code>s in any combination:</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">assert_eq!</span>(Val{v:<span class="number">3</span>} + Val{v:<span class="number">5</span>}, Val{v:<span class="number">8</span>});
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<span class="macro">assert_eq!</span>(Val{v:<span class="number">3</span>} + <span class="kw-2">&</span>Val{v:<span class="number">5</span>}, Val{v:<span class="number">8</span>});
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<span class="macro">assert_eq!</span>(<span class="kw-2">&</span>Val{v:<span class="number">3</span>} + Val{v:<span class="number">5</span>}, Val{v:<span class="number">8</span>});
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<span class="macro">assert_eq!</span>(<span class="kw-2">&</span>Val{v:<span class="number">3</span>} + <span class="kw-2">&</span>Val{v:<span class="number">5</span>}, Val{v:<span class="number">8</span>});</code></pre></div>
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<h2 id="binary-operators"><a href="#binary-operators">Binary operators</a></h2>
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<p>The general syntax to overload a binary operator between types <code><a_type></code> and <code><b_type></code> is:</p>
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<div class="example-wrap ignore"><a href="#" class="tooltip" title="This example is not tested">ⓘ</a><pre class="rust rust-example-rendered"><code><span class="macro">overload!</span>((<a_ident>: <a_type>) <op> (<b_ident>: <b_type>) -> <out_type> { <span class="comment">/*body*/ </span>});</code></pre></div>
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<p>Inside the body you can use <code><a_ident></code> and <code><b_ident></code> freely to perform any computation.</p>
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<p>The last line of the body needs to be an expression (i.e. no <code>;</code> at the end of the line) of type <code><out_type></code>.</p>
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<div><table><thead><tr><th>Operator</th><th>Example</th><th>Trait</th></tr></thead><tbody>
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<tr><td>+</td><td><code>overload!((a: A) + (b: B) -> C { /*...*/ );</code></td><td>Add</td></tr>
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<tr><td>-</td><td><code>overload!((a: A) - (b: B) -> C { /*...*/ );</code></td><td>Sub</td></tr>
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<tr><td>*</td><td><code>overload!((a: A) * (b: B) -> C { /*...*/ );</code></td><td>Mul</td></tr>
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<tr><td>/</td><td><code>overload!((a: A) / (b: B) -> C { /*...*/ );</code></td><td>Div</td></tr>
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<tr><td>%</td><td><code>overload!((a: A) % (b: B) -> C { /*...*/ );</code></td><td>Rem</td></tr>
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<tr><td>&</td><td><code>overload!((a: A) & (b: B) -> C { /*...*/ );</code></td><td>BitAnd</td></tr>
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<tr><td>|</td><td><code>overload!((a: A) | (b: B) -> C { /*…*/ );</code></td><td>BitOr</td></tr>
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<tr><td>^</td><td><code>overload!((a: A) ^ (b: B) -> C { /*...*/ );</code></td><td>BitXor</td></tr>
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<tr><td><<</td><td><code>overload!((a: A) << (b: B) -> C { /*...*/ );</code></td><td>Shl</td></tr>
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<tr><td>>></td><td><code>overload!((a: A) >> (b: B) -> C { /*...*/ );</code></td><td>Shr</td></tr>
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</tbody></table>
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</div><h2 id="assignment-operators"><a href="#assignment-operators">Assignment operators</a></h2>
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<p>The general syntax to overload an assignment operator between types <code><a_type></code> and <code><b_type></code> is:</p>
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<div class="example-wrap ignore"><a href="#" class="tooltip" title="This example is not tested">ⓘ</a><pre class="rust rust-example-rendered"><code><span class="macro">overload!</span>((<a_ident>: <span class="kw-2">&mut </span><a_type>) <op> (<b_ident>: <b_type>) { <span class="comment">/*body*/ </span>});</code></pre></div>
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<p>Inside the body you can use <code><a_ident></code> and <code><b_ident></code> freely to perform any computation and mutate <code><a_ident></code> as desired.</p>
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<div><table><thead><tr><th>Operator</th><th>Example</th><th>Trait</th></tr></thead><tbody>
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<tr><td>+=</td><td><code>overload!((a: &mut A) += (b: B) { /*...*/ );</code></td><td>AddAssign</td></tr>
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<tr><td>-=</td><td><code>overload!((a: &mut A) -= (b: B) { /*...*/ );</code></td><td>SubAssign</td></tr>
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<tr><td>*=</td><td><code>overload!((a: &mut A) *= (b: B) { /*...*/ );</code></td><td>MulAssign</td></tr>
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<tr><td>/=</td><td><code>overload!((a: &mut A) /= (b: B) { /*...*/ );</code></td><td>DivAssign</td></tr>
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<tr><td>%=</td><td><code>overload!((a: &mut A) %= (b: B) { /*...*/ );</code></td><td>RemAssign</td></tr>
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<tr><td>&=</td><td><code>overload!((a: &mut A) &= (b: B) { /*...*/ );</code></td><td>BitAndAssign</td></tr>
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<tr><td>|=</td><td><code>overload!((a: &mut A) |= (b: B) { /*…*/ );</code></td><td>BitOrAssign</td></tr>
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<tr><td>^=</td><td><code>overload!((a: &mut A) ^= (b: B) { /*...*/ );</code></td><td>BitXorAssign</td></tr>
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<tr><td><<=</td><td><code>overload!((a: &mut A) <<= (b: B) { /*...*/ );</code></td><td>ShlAssign</td></tr>
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<tr><td>>>=</td><td><code>overload!((a: &mut A) >>= (b: B) { /*...*/ );</code></td><td>ShrAssign</td></tr>
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</tbody></table>
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</div><h2 id="unary-operators"><a href="#unary-operators">Unary operators</a></h2>
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<p>The general syntax to overload a unary operator for type <code><a_type></code> is:</p>
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<div class="example-wrap ignore"><a href="#" class="tooltip" title="This example is not tested">ⓘ</a><pre class="rust rust-example-rendered"><code><span class="macro">overload!</span>(<op> (<a_ident>: <a_type>) -> <out_type> { <span class="comment">/*body*/ </span>});</code></pre></div>
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<p>Inside the body you can use <code><a_ident></code> freely to perform any computation.</p>
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<p>The last line of the body needs to be an expression (i.e. no <code>;</code> at the end of the line) of type <code><out_type></code>.</p>
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<div><table><thead><tr><th>Operator</th><th>Example</th><th>Trait</th></tr></thead><tbody>
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<tr><td>-</td><td><code>overload!(- (a: A) -> B { /*...*/ );</code></td><td>Neg</td></tr>
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<tr><td>!</td><td><code>overload!(! (a: A) -> B { /*...*/ );</code></td><td>Not</td></tr>
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</tbody></table>
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</div><h2 id="notes"><a href="#notes">Notes</a></h2>
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<p>Remember that you can only overload operators between one or more types if at least one of the types is defined in the current crate.</p>
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</div></details><h2 id="macros" class="section-header"><a href="#macros">Macros</a></h2><ul class="item-table"><li><div class="item-name"><a class="macro" href="macro.overload.html" title="macro overload::overload">overload</a></div><div class="desc docblock-short">Overloads an operator. See the <a href="index.html">module level documentation</a> for more information.</div></li></ul></section></div></main></body></html>
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