130 lines
5.3 KiB
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130 lines
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<h1 class='fqn'><span class='in-band'>Macro <a href='index.html'>error_chain</a>::<wbr><a class="macro" href=''>ensure</a></span><span class='out-of-band'><span id='render-detail'>
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<pre class="rust macro">
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<span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">ensure</span> {
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(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">cond</span>:<span class="ident">expr</span>, <span class="macro-nonterminal">$</span><span class="macro-nonterminal">e</span>:<span class="ident">expr</span>) <span class="op">=></span> { ... };
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}</pre>
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<div class='docblock'><p>Exits a function early with an error if the condition is not satisfied</p>
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<p>The <code>ensure!</code> macro is a convenience helper that provides a way to exit
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a function with an error if the given condition fails.</p>
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<p>As an example, <code>ensure!(condition, "error code: {}", errcode)</code> is equivalent to</p>
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<pre class="rust rust-example-rendered">
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<span class="kw">if</span> <span class="op">!</span><span class="ident">condition</span> {
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<span class="macro">bail</span><span class="macro">!</span>(<span class="string">"error code: {}"</span>, <span class="ident">errcode</span>);
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}</pre>
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<p>See documentation for <code>bail!</code> macro for further details.</p>
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