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        <p class='location'>Crate cfg_if</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#macros">Macros</a></li></ul></div><p class='location'></p><script>window.sidebarCurrent = {name: 'cfg_if', ty: 'mod', relpath: '../'};</script></div>
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<h1 class='fqn'><span class='in-band'>Crate <a class="mod" href=''>cfg_if</a></span><span class='out-of-band'><span id='render-detail'>
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               </span><a class='srclink' href='../src/cfg_if/lib.rs.html#1-133' title='goto source code'>[src]</a></span></h1>
<div class='docblock'><p>A macro for defining #[cfg] 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 #[cfg]'d blocks of code
without having to rewrite each clause multiple times.</p>
<h1 id="example" class="section-header"><a href="#example">Example</a></h1>
<pre class="rust rust-example-rendered">
<span class="attribute">#[<span class="ident">macro_use</span>]</span>
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">cfg_if</span>;

<span class="macro">cfg_if</span><span class="macro">!</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">&quot;32&quot;</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> }
    }
}
</pre>
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