1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>execution::prefer_only</title> 5<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../boost_asio.html" title="Boost.Asio"> 8<link rel="up" href="../reference.html" title="Reference"> 9<link rel="prev" href="execution__outstanding_work_t__untracked_t/value.html" title="execution::outstanding_work_t::untracked_t::value"> 10<link rel="next" href="execution__prefer_only/is_applicable_property_v.html" title="execution::prefer_only::is_applicable_property_v"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> 15<td align="center"><a href="../../../../index.html">Home</a></td> 16<td 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name="boost_asio.reference.execution__prefer_only"></a><a class="link" href="execution__prefer_only.html" title="execution::prefer_only">execution::prefer_only</a> 28</h3></div></div></div> 29<p> 30 A property adapter that is used with the polymorphic executor wrapper to 31 mark properties as preferable, but not requirable. 32 </p> 33<pre class="programlisting">template< 34 typename Property> 35struct prefer_only 36</pre> 37<h5> 38<a name="boost_asio.reference.execution__prefer_only.h0"></a> 39 <span class="phrase"><a name="boost_asio.reference.execution__prefer_only.types"></a></span><a class="link" href="execution__prefer_only.html#boost_asio.reference.execution__prefer_only.types">Types</a> 40 </h5> 41<div class="informaltable"><table class="table"> 42<colgroup> 43<col> 44<col> 45</colgroup> 46<thead><tr> 47<th> 48 <p> 49 Name 50 </p> 51 </th> 52<th> 53 <p> 54 Description 55 </p> 56 </th> 57</tr></thead> 58<tbody><tr> 59<td> 60 <p> 61 <a class="link" href="execution__prefer_only/polymorphic_query_result_type.html" title="execution::prefer_only::polymorphic_query_result_type"><span class="bold"><strong>polymorphic_query_result_type</strong></span></a> 62 </p> 63 </td> 64<td> 65 <p> 66 The type returned by queries against an any_executor. 67 </p> 68 </td> 69</tr></tbody> 70</table></div> 71<h5> 72<a name="boost_asio.reference.execution__prefer_only.h1"></a> 73 <span class="phrase"><a name="boost_asio.reference.execution__prefer_only.data_members"></a></span><a class="link" href="execution__prefer_only.html#boost_asio.reference.execution__prefer_only.data_members">Data Members</a> 74 </h5> 75<div class="informaltable"><table class="table"> 76<colgroup> 77<col> 78<col> 79</colgroup> 80<thead><tr> 81<th> 82 <p> 83 Name 84 </p> 85 </th> 86<th> 87 <p> 88 Description 89 </p> 90 </th> 91</tr></thead> 92<tbody> 93<tr> 94<td> 95 <p> 96 <a class="link" href="execution__prefer_only/is_applicable_property_v.html" title="execution::prefer_only::is_applicable_property_v"><span class="bold"><strong>is_applicable_property_v</strong></span></a> <span class="silver">[static]</span> 97 </p> 98 </td> 99<td> 100 <p> 101 The prefer_only adapter applies to the same types as the nested 102 property. 103 </p> 104 </td> 105</tr> 106<tr> 107<td> 108 <p> 109 <a class="link" href="execution__prefer_only/is_preferable.html" title="execution::prefer_only::is_preferable"><span class="bold"><strong>is_preferable</strong></span></a> <span class="silver">[static]</span> 110 </p> 111 </td> 112<td> 113 <p> 114 The context_t property can be preferred, it the underlying property 115 can be preferred. 116 </p> 117 </td> 118</tr> 119<tr> 120<td> 121 <p> 122 <a class="link" href="execution__prefer_only/is_requirable.html" title="execution::prefer_only::is_requirable"><span class="bold"><strong>is_requirable</strong></span></a> <span class="silver">[static]</span> 123 </p> 124 </td> 125<td> 126 <p> 127 The context_t property cannot be required. 128 </p> 129 </td> 130</tr> 131</tbody> 132</table></div> 133<h5> 134<a name="boost_asio.reference.execution__prefer_only.h2"></a> 135 <span class="phrase"><a name="boost_asio.reference.execution__prefer_only.requirements"></a></span><a class="link" href="execution__prefer_only.html#boost_asio.reference.execution__prefer_only.requirements">Requirements</a> 136 </h5> 137<p> 138 <span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/execution/prefer_only.hpp</code> 139 </p> 140<p> 141 <span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio/execution.hpp</code> 142 </p> 143</div> 144<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 145<td align="left"></td> 146<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 147 Kohlhoff<p> 148 Distributed under the Boost Software License, Version 1.0. (See accompanying 149 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 150 </p> 151</div></td> 152</tr></table> 153<hr> 154<div class="spirit-nav"> 155<a accesskey="p" href="execution__outstanding_work_t__untracked_t/value.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="execution__prefer_only/is_applicable_property_v.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 156</div> 157</body> 158</html> 159
