98 lines
5.2 KiB
HTML
98 lines
5.2 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html><meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<title>C Macro API Reference - Boost.Outcome documentation</title>
|
|
<link rel="stylesheet" href="../../css/boost.css" type="text/css">
|
|
<meta name="generator" content="Hugo 0.52 with Boostdoc theme">
|
|
<meta name="viewport" content="width=device-width,initial-scale=1.0"/>
|
|
|
|
<link rel="icon" href="../../images/favicon.ico" type="image/ico"/>
|
|
<body><div class="spirit-nav">
|
|
<a accesskey="p" href="../../experimental/c-api/example2.html"><img src="../../images/prev.png" alt="Prev"></a>
|
|
<a accesskey="u" href="../../experimental/c-api.html"><img src="../../images/up.png" alt="Up"></a>
|
|
<a accesskey="h" href="../../index.html"><img src="../../images/home.png" alt="Home"></a><a accesskey="n" href="../../reference.html"><img src="../../images/next.png" alt="Next"></a></div><div id="content">
|
|
<div class="titlepage"><div><div><h1 style="clear: both">C Macro API Reference</h1></div></div></div>
|
|
|
|
|
|
<p>The C macro API header <code><boost/outcome/experimental/result.h></code> consists of these macros:</p>
|
|
|
|
<dl>
|
|
<dt><code>BOOST_OUTCOME_C_DECLARE_RESULT(ident, T, E)</code>
|
|
<dd>Declares to C a <code>basic_result<T, E></code> type uniquely
|
|
identified by <code>ident</code>. <code>T</code> is available at the
|
|
member variable <code>.value</code>, and <code>E</code> is available
|
|
at the member variable <code>.error</code>.
|
|
|
|
<dt><code>BOOST_OUTCOME_C_RESULT(ident)</code>
|
|
<dd>A reference to a previously declared <code>result</code> type with
|
|
unique <code>ident</code>.
|
|
|
|
<dt><code>BOOST_OUTCOME_C_RESULT_HAS_VALUE(r)</code>
|
|
<dd>Evaluates to 1 (true) if the input <code>result</code> has a value.
|
|
|
|
<dt><code>BOOST_OUTCOME_C_RESULT_HAS_ERROR(r)</code>
|
|
<dd>Evaluates to 1 (true) if the input <code>result</code> has an error.
|
|
|
|
<dt><code>BOOST_OUTCOME_C_RESULT_ERROR_IS_ERRNO(r)</code>
|
|
<dd>Evaluates to 1 (true) if the input <code>result</code>'s error value
|
|
is a code in the POSIX <code>errno</code> domain.
|
|
</dl>
|
|
|
|
<p>The above let you work, somewhat awkwardly, with any C-compatible
|
|
<code>basic_result<T, E></code>. <code>basic_result<T, E></code> is trivially copyable and
|
|
standard layout if its <code>T</code> and <code>E</code> are both so, and it has the C layout:</p>
|
|
<div class="highlight"><pre class="chroma"><code class="language-c++" data-lang="c++"><span class="k">struct</span> <span class="n">cxx_result_</span><span class="cp">##ident
|
|
</span><span class="cp"></span><span class="p">{</span>
|
|
<span class="n">T</span> <span class="n">value</span><span class="p">;</span>
|
|
<span class="kt">unsigned</span> <span class="n">flags</span><span class="p">;</span>
|
|
<span class="n">E</span> <span class="n">error</span><span class="p">;</span>
|
|
<span class="p">};</span>
|
|
</code></pre></div>
|
|
<h3 id="system-error2-support"><code><system_error2></code> support</h3>
|
|
|
|
<dl>
|
|
<dt><code>BOOST_OUTCOME_C_DECLARE_STATUS_CODE(ident, value_type)</code>
|
|
<dd>Declares to C a status code type with domain <code>value_type</code>
|
|
available at the member variable <code>.value</code>. The <code>ident</code>
|
|
must be any identifier fragment unique in this translation unit. It is
|
|
used to uniquely identify this status code type in other macros.
|
|
|
|
<dt><code>BOOST_OUTCOME_C_STATUS_CODE(ident)</code>
|
|
<dd>A reference to a previously declared status code type with unique
|
|
<code>ident</code>.
|
|
</dl>
|
|
|
|
<p>There is a high likelihood that C++ functions regularly called by C
|
|
code will return their failures either in erased <code>system_code</code>
|
|
or in <code>posix_code</code> (i.e. <code>errno</code> code domain). Via querying the
|
|
returned value using <code>BOOST_OUTCOME_C_RESULT_ERROR_IS_ERRNO(r)</code>, one can determine
|
|
if the returned code is in the <code>errno</code> code domain, and thus can be
|
|
fed to <code>strerror()</code> and so on. Therefore there are
|
|
convenience macro APIs for those particular use cases.</p>
|
|
|
|
<dl>
|
|
<dt><code>BOOST_OUTCOME_C_DECLARE_RESULT_ERRNO(ident, T)</code>
|
|
<dd>Declares to C a <code>basic_result<T, posix_code></code>
|
|
type uniquely identified by <code>ident</code>.
|
|
|
|
<dt><code>BOOST_OUTCOME_C_RESULT_ERRNO(ident)</code>
|
|
<dd>A reference to a previously declared <code>basic_result<T, posix_code></code>
|
|
type with unique <code>ident</code>.
|
|
|
|
<dt><code>BOOST_OUTCOME_C_DECLARE_RESULT_SYSTEM(ident, T)</code>
|
|
<dd>Declares to C a <code>basic_result<T, system_code></code>
|
|
type uniquely identified by <code>ident</code>.
|
|
|
|
<dt><code>BOOST_OUTCOME_C_RESULT_SYSTEM(ident)</code>
|
|
<dd>A reference to a previously declared <code>basic_result<T, system_code></code>
|
|
type with unique <code>ident</code>.
|
|
</dl>
|
|
|
|
|
|
</div><p><small>Last revised: February 05, 2019 at 17:14:18 UTC</small></p>
|
|
<hr>
|
|
<div class="spirit-nav">
|
|
<a accesskey="p" href="../../experimental/c-api/example2.html"><img src="../../images/prev.png" alt="Prev"></a>
|
|
<a accesskey="u" href="../../experimental/c-api.html"><img src="../../images/up.png" alt="Up"></a>
|
|
<a accesskey="h" href="../../index.html"><img src="../../images/home.png" alt="Home"></a><a accesskey="n" href="../../reference.html"><img src="../../images/next.png" alt="Next"></a></div></body>
|
|
</html>
|