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49 lines
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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="The standard logging macro."><title>log in log - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="log" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../static.files/storage-e2aeef58.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-263c88ec.css"></noscript><link rel="icon" href="https://prev.rust-lang.org/favicon.ico"></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]--><rustdoc-topbar><h2><a href="#">log</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><a class="logo-container" href="../log/index.html"><img src="https://prev.rust-lang.org/logos/rust-logo-128x128-blk-v2.png" alt="logo"></a><h2><a href="../log/index.html">log</a><span class="version">0.4.29</span></h2></div><div class="sidebar-elems"><div id="rustdoc-modnav"></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="index.html">log</a></div><h1>Macro <span class="macro">log</span> <button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../src/log/macros.rs.html#75-115">Source</a> </span></div><pre class="rust item-decl"><code>macro_rules! log {
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(logger: $logger:expr, target: $target:expr, $lvl:expr, $($arg:tt)+) => { ... };
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(logger: $logger:expr, $lvl:expr, $($arg:tt)+) => { ... };
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(target: $target:expr, $lvl:expr, $($arg:tt)+) => { ... };
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($lvl:expr, $($arg:tt)+) => { ... };
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}</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>The standard logging macro.</p>
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<p>This macro will generically log with the specified <code>Level</code> and <code>format!</code>
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based argument list.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>log::{log, Level};
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<span class="kw">let </span>data = (<span class="number">42</span>, <span class="string">"Forty-two"</span>);
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<span class="kw">let </span>private_data = <span class="string">"private"</span>;
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<span class="macro">log!</span>(Level::Error, <span class="string">"Received errors: {}, {}"</span>, data.<span class="number">0</span>, data.<span class="number">1</span>);</code></pre></div>
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<p>Optionally, you can specify a <code>target</code> argument to attach a specific target
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to the log record. By default, the target is the module path of the caller.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>log::{log, Level};
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<span class="kw">let </span>data = (<span class="number">42</span>, <span class="string">"Forty-two"</span>);
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<span class="kw">let </span>private_data = <span class="string">"private"</span>;
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<span class="macro">log!</span>(
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target: <span class="string">"app_events"</span>,
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Level::Error,
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<span class="string">"Received errors: {}, {}"</span>,
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data.<span class="number">0</span>, data.<span class="number">1
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</span>);</code></pre></div>
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<p>And optionally, you can specify a <code>logger</code> argument to use a specific logger
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instead of the default global logger.</p>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>log::{log, Level, Log};
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<span class="kw">let </span>data = (<span class="number">42</span>, <span class="string">"Forty-two"</span>);
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<span class="kw">let </span>private_data = <span class="string">"private"</span>;
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<span class="kw">let </span>my_logger = MyLogger {};
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<span class="macro">log!</span>(
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logger: my_logger,
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Level::Error,
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<span class="string">"Received errors: {}, {}"</span>,
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data.<span class="number">0</span>, data.<span class="number">1
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</span>);</code></pre></div>
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<p>The <code>logger</code> argument accepts a value that implements the <code>Log</code> trait. The value
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will be borrowed within the macro.</p>
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<p>Note that the global level set via Cargo features, or through <code>set_max_level</code> will
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still apply, even when a custom logger is supplied with the <code>logger</code> argument.</p>
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</div></details></section></div></main></body></html> |