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   1 <!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="Adds `core::fmt` trait implementations to type `$ty`."><title>impl_fmt_traits in bdk_chain::bitcoin::hashes::hex::display - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-46f98efaafac5295.ttf.woff2,FiraSans-Regular-018c141bf0843ffd.woff2,FiraSans-Medium-8f9a781e4970d388.woff2,SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2,SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../../../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../../../../static.files/rustdoc-dd39b87e5fcfba68.css"><meta name="rustdoc-vars" data-root-path="../../../../../" data-static-root-path="../../../../../static.files/" data-current-crate="bdk_chain" data-themes="" data-resource-suffix="" data-rustdoc-version="1.80.0-nightly (78a775127 2024-05-11)" data-channel="nightly" data-search-js="search-d52510db62a78183.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../../../../../static.files/storage-118b08c4c78b968e.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../../../../static.files/main-20a3ad099b048cf2.js"></script><noscript><link rel="stylesheet" href="../../../../../static.files/noscript-df360f571f6edeae.css"></noscript><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 macro"><!--[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" title="show sidebar"></button><a class="logo-container" href="../../../../../bdk_chain/index.html"><img src="https://github.com/bitcoindevkit/bdk/raw/master/static/bdk.png" alt=""></a></nav><nav class="sidebar"><div class="sidebar-crate"><a class="logo-container" href="../../../../../bdk_chain/index.html"><img src="https://github.com/bitcoindevkit/bdk/raw/master/static/bdk.png" alt="logo"></a><h2><a href="../../../../../bdk_chain/index.html">bdk_chain</a><span class="version">0.17.0</span></h2></div><div class="sidebar-elems"><h2><a href="index.html">In bdk_chain::bitcoin::hashes::hex::display</a></h2></div></nav><div class="sidebar-resizer"></div><main><div class="width-limiter"><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><h1>Macro <a href="../../../../index.html">bdk_chain</a>::<wbr><a href="../../../index.html">bitcoin</a>::<wbr><a href="../../index.html">hashes</a>::<wbr><a href="../index.html">hex</a>::<wbr><a href="index.html">display</a>::<wbr><a class="macro" href="#">impl_fmt_traits</a><button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><span class="out-of-band"><button id="toggle-all-docs" title="collapse all docs">[<span>&#x2212;</span>]</button></span></div><pre class="rust item-decl"><span class="macro">macro_rules!</span> impl_fmt_traits {
   2     (<span class="kw">impl </span>fmt_traits <span class="kw">for </span><span class="macro-nonterminal">$ty</span>:ident { <span class="kw">const </span>LENGTH: usize = <span class="macro-nonterminal">$len</span>:expr; }) =&gt; { ... };
   3     (<span class="attr">#[display_backward(<span class="macro-nonterminal">$reverse</span>:expr)] </span><span class="kw">impl </span>fmt_traits <span class="kw">for </span><span class="macro-nonterminal">$ty</span>:ident { <span class="kw">const </span>LENGTH: usize = <span class="macro-nonterminal">$len</span>:expr; }) =&gt; { ... };
   4     (<span class="kw">impl</span>&lt;$(<span class="macro-nonterminal">$gen</span>:ident: <span class="macro-nonterminal">$gent</span>:ident),<span class="kw-2">*</span>&gt; fmt_traits <span class="kw">for </span><span class="macro-nonterminal">$ty</span>:ident&lt;$(<span class="macro-nonterminal">$unused</span>:ident),<span class="kw-2">*</span>&gt; { <span class="kw">const </span>LENGTH: usize = <span class="macro-nonterminal">$len</span>:expr; }) =&gt; { ... };
   5     (<span class="attr">#[display_backward(<span class="macro-nonterminal">$reverse</span>:expr)] </span><span class="kw">impl</span>&lt;$(<span class="macro-nonterminal">$gen</span>:ident: <span class="macro-nonterminal">$gent</span>:ident),<span class="kw-2">*</span>&gt; fmt_traits <span class="kw">for </span><span class="macro-nonterminal">$ty</span>:ident&lt;$(<span class="macro-nonterminal">$unused</span>:ident),<span class="kw-2">*</span>&gt; { <span class="kw">const </span>LENGTH: usize = <span class="macro-nonterminal">$len</span>:expr; }) =&gt; { ... };
   6 }</pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Adds <code>core::fmt</code> trait implementations to type <code>$ty</code>.</p>
   7 <p>Implements:</p>
   8 <ul>
   9 <li><code>fmt::{LowerHex, UpperHex}</code> using <a href="../macro.fmt_hex_exact.html" title="macro bdk_chain::bitcoin::hashes::hex::fmt_hex_exact"><code>fmt_hex_exact</code></a>.</li>
  10 <li><code>fmt::{Display, Debug}</code> by calling <code>LowerHex</code>.</li>
  11 </ul>
  12 <p>Requires:</p>
  13 <ul>
  14 <li><code>$ty</code> must implement <code>IntoIterator&lt;Item=Borrow&lt;u8&gt;&gt;</code>.</li>
  15 </ul>
  16 <h3 id="parameters"><a class="doc-anchor" href="#parameters">§</a>Parameters</h3>
  17 <ul>
  18 <li><code>$ty</code> - the type to implement traits on.</li>
  19 <li><code>$len</code> - known length of <code>$bytes</code>, must be a const expression.</li>
  20 <li><code>$bytes</code> - bytes to be encoded, most likely a reference to an array.</li>
  21 <li><code>$reverse</code> - true if you want the array to be displayed backwards.</li>
  22 <li><code>$gen: $gent</code> - optional generic type(s) and trait bound(s) to put on <code>$ty</code> e.g, <code>F: Foo</code>.</li>
  23 </ul>
  24 <h3 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h3>
  25 <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">struct </span>Wrapper([u8; <span class="number">4</span>]);
  26
  27 <span class="kw">impl </span>Borrow&lt;[u8]&gt; <span class="kw">for </span>Wrapper {
  28     <span class="kw">fn </span>borrow(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>[u8] { <span class="kw-2">&amp;</span><span class="self">self</span>.<span class="number">0</span>[..] }
  29 }
  30
  31 <span class="macro">impl_fmt_traits!</span> {
  32     <span class="kw">impl </span>fmt_traits <span class="kw">for </span>Wrapper {
  33         <span class="kw">const </span>LENGTH: usize = <span class="number">4</span>;
  34     }
  35 }
  36
  37 <span class="kw">let </span>w = Wrapper([<span class="number">0x12</span>, <span class="number">0x34</span>, <span class="number">0x56</span>, <span class="number">0x78</span>]);
  38 <span class="macro">assert_eq!</span>(<span class="macro">format!</span>(<span class="string">"{}"</span>, w), <span class="string">"12345678"</span>);</code></pre></div>
  39 <p>We support generics on <code>$ty</code>:</p>
  40
  41 <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">struct </span>Wrapper&lt;T&gt;([u8; <span class="number">4</span>], PhantomData&lt;T&gt;);
  42
  43 <span class="comment">// `Clone` is just some arbitrary trait.
  44 </span><span class="kw">impl</span>&lt;T: Clone&gt; Borrow&lt;[u8]&gt; <span class="kw">for </span>Wrapper&lt;T&gt; {
  45     <span class="kw">fn </span>borrow(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>[u8] { <span class="kw-2">&amp;</span><span class="self">self</span>.<span class="number">0</span>[..] }
  46 }
  47
  48 <span class="macro">impl_fmt_traits!</span> {
  49     <span class="kw">impl</span>&lt;T: Clone&gt; fmt_traits <span class="kw">for </span>Wrapper&lt;T&gt; {
  50         <span class="kw">const </span>LENGTH: usize = <span class="number">4</span>;
  51     }
  52 }
  53
  54 <span class="kw">let </span>w = Wrapper([<span class="number">0x12</span>, <span class="number">0x34</span>, <span class="number">0x56</span>, <span class="number">0x78</span>], PhantomData::&lt;u32&gt;);
  55 <span class="macro">assert_eq!</span>(<span class="macro">format!</span>(<span class="string">"{}"</span>, w), <span class="string">"12345678"</span>);</code></pre></div>
  56 <p>And also, as is required by <code>rust-bitcoin</code>, we support displaying
  57 the hex string byte-wise backwards:</p>
  58
  59 <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">struct </span>Wrapper([u8; <span class="number">4</span>]);
  60
  61 <span class="kw">impl </span>Borrow&lt;[u8]&gt; <span class="kw">for </span>Wrapper {
  62     <span class="kw">fn </span>borrow(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>[u8] { <span class="kw-2">&amp;</span><span class="self">self</span>.<span class="number">0</span>[..] }
  63 }
  64
  65 <span class="macro">impl_fmt_traits!</span> {
  66     <span class="attr">#[display_backward(<span class="bool-val">true</span>)]
  67     </span><span class="kw">impl </span>fmt_traits <span class="kw">for </span>Wrapper {
  68         <span class="kw">const </span>LENGTH: usize = <span class="number">4</span>;
  69     }
  70 }
  71 <span class="kw">let </span>w = Wrapper([<span class="number">0x12</span>, <span class="number">0x34</span>, <span class="number">0x56</span>, <span class="number">0x78</span>]);
  72 <span class="macro">assert_eq!</span>(<span class="macro">format!</span>(<span class="string">"{}"</span>, w), <span class="string">"78563412"</span>);</code></pre></div>
  73 </div></details></section></div></main></body></html>