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| <details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>A macro for defining <code>#[cfg]</code> if-else statements.</p> |
| <p>The macro provided by this crate, <code>cfg_if</code>, is similar to the <code>if/elif</code> C |
| preprocessor macro by allowing definition of a cascade of <code>#[cfg]</code> cases, |
| emitting the implementation which matches first.</p> |
| <p>This allows you to conveniently provide a long list <code>#[cfg]</code>’d blocks of code |
| without having to rewrite each clause multiple times.</p> |
| <h2 id="example" class="section-header"><a href="#example">Example</a></h2> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="macro">cfg_if::cfg_if!</span> { |
| <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">unix</span>)]</span> { |
| <span class="kw">fn</span> <span class="ident">foo</span>() { <span class="comment">/* unix specific functionality */</span> } |
| } <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">target_pointer_width</span> <span class="op">=</span> <span class="string">"32"</span>)]</span> { |
| <span class="kw">fn</span> <span class="ident">foo</span>() { <span class="comment">/* non-unix, 32-bit functionality */</span> } |
| } <span class="kw">else</span> { |
| <span class="kw">fn</span> <span class="ident">foo</span>() { <span class="comment">/* fallback implementation */</span> } |
| } |
| } |
| </code></pre></div> |
| </div></details><h2 id="macros" class="small-section-header"><a href="#macros">Macros</a></h2> |
| <div class="item-table"><div class="item-row"><div class="item-left module-item"><a class="macro" href="macro.cfg_if.html" title="cfg_if::cfg_if macro">cfg_if</a></div><div class="item-right docblock-short"><p>The main macro provided by this crate. See crate documentation for more |
| information.</p> |
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