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| 24 | </div> | |
| 25 | <div class="section"> | |
| 26 | <div class="titlepage"><div><div><h4 class="title"> | |
| 27 | <a name="fiber.when_any.when_any.when_any__a_dubious_alternative"></a><a class="link" href="when_any__a_dubious_alternative.html" title="when_any, a dubious alternative">when_any, | |
| 28 | a dubious alternative</a> | |
| 29 | </h4></div></div></div> | |
| 30 | <p> | |
| 31 | Certain topics in C++ can arouse strong passions, and exceptions are no | |
| 32 | exception. We cannot resist mentioning — for purely informational purposes | |
| 33 | — that when you need only the <span class="emphasis"><em>first</em></span> result from some | |
| 34 | number of concurrently-running fibers, it would be possible to pass a | |
| 35 | <code class="literal">shared_ptr<<a class="link" href="../../synchronization/futures/promise.html#class_promise"><code class="computeroutput">promise<></code></a>></code> to the | |
| 36 | participating fibers, then cause the initiating fiber to call <a class="link" href="../../synchronization/futures/future.html#future_get"><code class="computeroutput">future::get()</code></a> on | |
| 37 | its <a class="link" href="../../synchronization/futures/future.html#class_future"><code class="computeroutput">future<></code></a>. The first fiber to call <a class="link" href="../../synchronization/futures/promise.html#promise_set_value"><code class="computeroutput">promise::set_value()</code></a> on | |
| 38 | that shared <code class="computeroutput"><span class="identifier">promise</span></code> will | |
| 39 | succeed; subsequent <code class="computeroutput"><span class="identifier">set_value</span><span class="special">()</span></code> calls on the same <code class="computeroutput"><span class="identifier">promise</span></code> | |
| 40 | instance will throw <code class="computeroutput"><span class="identifier">future_error</span></code>. | |
| 41 | </p> | |
| 42 | <p> | |
| 43 | Use this information at your own discretion. Beware the dark side. | |
| 44 | </p> | |
| 45 | </div> | |
| 46 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
| 47 | <td align="left"></td> | |
| 48 | <td align="right"><div class="copyright-footer">Copyright © 2013 Oliver Kowalke<p> | |
| 49 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| 50 | 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>) | |
| 51 | </p> | |
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