1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html><meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 3<title>failure_type<EC, EP = void> - Boost.Outcome documentation</title> 4<link rel="stylesheet" href="../../css/boost.css" type="text/css"> 5<meta name="generator" content="Hugo 0.52 with Boostdoc theme"> 6<meta name="viewport" content="width=device-width,initial-scale=1.0"/> 7 8<link rel="icon" href="../../images/favicon.ico" type="image/ico"/> 9<body><div class="spirit-nav"> 10<a accesskey="p" href="../../reference/types/awaitables/eager.html"><img src="../../images/prev.png" alt="Prev"></a> 11 <a accesskey="u" href="../../reference/types.html"><img src="../../images/up.png" alt="Up"></a> 12 <a accesskey="h" href="../../index.html"><img src="../../images/home.png" alt="Home"></a><a accesskey="n" href="../../reference/types/in_place_type_t.html"><img src="../../images/next.png" alt="Next"></a></div><div id="content"> 13 <div class="titlepage"><div><div><h1 style="clear: both"><code>failure_type<EC, EP = void></code></h1></div></div></div> 14 <p>Type sugar for constructing an unsuccessful result or outcome. Generally not constructed directly, but via the free function <a href="../../reference/functions/failure.html" class="api-reference"><code>failure(T &&, ...)</code></a> 15. Detectable using <a href="../../reference/traits/is_failure_type.html" class="api-reference"><code>is_failure_type<T></code></a> 16.</p> 17 18<p>This is a regular wrapper type, with defaulted default, copy and move constructor, defaulted assignment, and defaulted destructor.</p> 19 20<p>Member type aliases <code>error_type</code> and <code>exception_type</code> indicate <code>EC</code> and <code>E</code>.</p> 21 22<p>There is an explicit initialising constructor taking any types <code>U</code> and <code>V</code> which will forward construct the contained <code>error_type</code> and <code>exception_type</code> respectively.</p> 23 24<p>There are two tagged initialising constructors taking <code>in_place_type_t<error_type></code> or <code>in_place_type_t<exception_type></code>, and a <code>U</code> which will forward construct the contained <code>error_type</code> and <code>exception_type</code> respectively.</p> 25 26<p>There are <code>.error()</code> and <code>.exception()</code> reference observers with the usual constexpr lvalue, const lvalue, rvalue and const rvalue overloads. One can discover which or both of these is valid using the usual <code>.has_error()</code> and <code>.has_exception()</code> observers.</p> 27 28<p>There are specialisations <code>failure_type<EC, void></code> and <code>failure_type<void, E></code> which store nothing for the voided type and do not provide their observer functions.</p> 29 30<p><em>Requires</em>: Nothing.</p> 31 32<p><em>Namespace</em>: <code>BOOST_OUTCOME_V2_NAMESPACE</code></p> 33 34<p><em>Header</em>: <code><boost/outcome/success_failure.hpp></code></p> 35 36 37 </div><p><small>Last revised: January 24, 2019 at 01:15:16 UTC</small></p> 38<hr> 39<div class="spirit-nav"> 40<a accesskey="p" href="../../reference/types/awaitables/eager.html"><img src="../../images/prev.png" alt="Prev"></a> 41 <a accesskey="u" href="../../reference/types.html"><img src="../../images/up.png" alt="Up"></a> 42 <a accesskey="h" href="../../index.html"><img src="../../images/home.png" alt="Home"></a><a accesskey="n" href="../../reference/types/in_place_type_t.html"><img src="../../images/next.png" alt="Next"></a></div></body> 43</html> 44
