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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="Tests whether a span with the specified level and target would be enabled."><title>span_enabled in tracing - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Regular-0fe48ade.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" crossorigin href="../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../static.files/rustdoc-42caa33d.css"><meta name="rustdoc-vars" data-root-path="../" data-static-root-path="../static.files/" data-current-crate="tracing" data-themes="" data-resource-suffix="" data-rustdoc-version="1.84.0 (9fc6b4312 2025-01-07)" data-channel="1.84.0" data-search-js="search-92e6798f.js" data-settings-js="settings-0f613d39.js" ><script src="../static.files/storage-59e33391.js"></script><script defer src="sidebar-items.js"></script><script defer src="../static.files/main-5f194d8c.js"></script><noscript><link rel="stylesheet" href="../static.files/noscript-893ab5e7.css"></noscript><link rel="alternate icon" type="image/png" href="../static.files/favicon-32x32-6580c154.png"><link rel="icon" type="image/svg+xml" href="../static.files/favicon-044be391.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="../tracing/index.html"><img src="https://raw.githubusercontent.com/tokio-rs/tracing/master/assets/logo-type.png" alt=""></a></nav><nav class="sidebar"><div class="sidebar-crate"><a class="logo-container" href="../tracing/index.html"><img src="https://raw.githubusercontent.com/tokio-rs/tracing/master/assets/logo-type.png" alt="logo"></a><h2><a href="../tracing/index.html">tracing</a><span class="version">0.1.40</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">span_<wbr>enabled</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#examples" title="Examples">Examples</a></li></ul></section><div id="rustdoc-modnav"><h2 class="in-crate"><a href="index.html">In crate tracing</a></h2></div></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"><span class="rustdoc-breadcrumbs"><a href="index.html">tracing</a></span><h1>Macro <span class="macro">span_enabled</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/tracing/macros.rs.html#1087-1091">Source</a> </span></div><pre class="rust item-decl"><code>macro_rules! span_enabled {
($($rest:tt)*) =&gt; { ... };
}</code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Tests whether a span with the specified level and target would be enabled.</p>
<p>This is similar to <a href="macro.enabled.html" title="macro tracing::enabled"><code>enabled!</code></a>, but queries the current subscriber specifically for
an event, whereas <a href="macro.enabled.html" title="macro tracing::enabled"><code>enabled!</code></a> queries for an event <em>or</em> span.</p>
<p>See the documentation for [<code>enabled!]</code> for more details on using this macro.
See also <a href="macro.span_enabled.html" title="macro tracing::span_enabled"><code>span_enabled!</code></a>.</p>
<h2 id="examples"><a class="doc-anchor" href="#examples">§</a>Examples</h2>
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">if </span><span class="macro">span_enabled!</span>(target: <span class="string">"my_crate"</span>, Level::DEBUG) {
<span class="comment">// some expensive work...
</span>}
<span class="comment">// simpler
</span><span class="kw">if </span><span class="macro">span_enabled!</span>(Level::DEBUG) {
<span class="comment">// some expensive work...
</span>}
<span class="comment">// with fields
</span><span class="kw">if </span><span class="macro">span_enabled!</span>(Level::DEBUG, foo_field) {
<span class="comment">// some expensive work...
</span>}</code></pre></div>
</div></details></section></div></main></body></html>