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>Experimental - 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="./recipes/foreign-try.html"><img src="./images/prev.png" alt="Prev"></a> 11 <a accesskey="u" href="./index.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="./experimental/advantages.html"><img src="./images/next.png" alt="Next"></a></div><div id="content"> 13 14 <div class="titlepage"><div><div><h1 style="clear: both">Experimental</h1></div></div></div> 15<p>In <code><boost/outcome/experimental></code>, there ships an Outcome-based simulation of 16the proposed <a href="https://wg21.link/P1095">P1095 <em>Zero overhead deterministic failure</em></a> 17specific implementation of <a href="http://wg21.link/P0709">P0709 <em>Zero overhead exceptions: Throwing values</em></a>, aka “Herbceptions”. This library-only implementation lets you use a close simulacrum 18of potential future C++ lightweight exceptions today in <a href="./requirements.html">any C++ 14 compiler 19which Outcome supports</a>.</p> 20 21<div class="notices warning" style="background: url('images/warning.png') top left no-repeat padding-box padding-box;"> 22<div class="notices heading">warning</div> 23<div class="notices message"><p><b>It is stressed, in the strongest possible terms, that any item inside 24<code><boost/outcome/experimental></code> is subject to unannounced breaking change based 25on WG21 standards committee feedback</b>. That said, the chances are high 26that most of those breaking changes will be to naming rather than to 27fundamental semantics, so you can upgrade with a bit of find and replace. 28There are quite a few large code bases out there 29already using this experimental support in anger, we know it works well 30at scale and it’s a good bit superior to <code>std::error_code</code> et al on every 31measure.</p> 32</div> 33</div> 34 35 36<p>P1095’s support library has a reference implementation at <a href="https://ned14.github.io/status-code/">https://ned14.github.io/status-code/</a>. 37You will find terse documentation there, and an API reference. 38This library is wholly incorporated into Outcome in the <code><boost/outcome/experimental/status-code></code> 39directory, with bindings into Outcome provided in the following headers:</p> 40 41<ul> 42<li><code><boost/outcome/experimental/status_result.hpp></code></li> 43<li><code><boost/outcome/experimental/status_outcome.hpp></code></li> 44</ul> 45 46<p>These headers import the entire contents of the <code>BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE</code> 47namespace into the <code>BOOST_OUTCOME_V2_NAMESPACE::experimental</code> namespace. You 48can thus address everything in <code>BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE</code> via 49<code>BOOST_OUTCOME_V2_NAMESPACE::experimental</code>.</p> 50 51<p>As P1095 also proposes C language support for lightweight C++ exceptions, 52experimental Outcome also has a macro-based C interface that enables C 53code to work with the C-compatible subset of <code>status_result<T, E></code>:</p> 54 55<ul> 56<li><code><boost/outcome/experimental/result.h></code></li> 57</ul> 58 59<p>For non-Windows non-POSIX platforms such as some embedded systems, standalone 60Experimental Outcome can be used with the <code>BOOST_OUTCOME_SYSTEM_ERROR2_NOT_POSIX</code> macro 61defined. This does not include POSIX headers, and makes available a high fidelity, 62fully deterministic, alternative to C++ exceptions on such platforms.</p> 63 64 65 66 </div><p><small>Last revised: February 25, 2020 at 11:15:13 UTC</small></p> 67<hr> 68<div class="spirit-nav"> 69<a accesskey="p" href="./recipes/foreign-try.html"><img src="./images/prev.png" alt="Prev"></a> 70 <a accesskey="u" href="./index.html"><img src="./images/up.png" alt="Up"></a> 71 <a accesskey="h" href="./index.html"><img src="./images/home.png" alt="Home"></a><a accesskey="n" href="./experimental/advantages.html"><img src="./images/next.png" alt="Next"></a></div></body> 72</html> 73
