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| The flags are implemented as a const data member of the facet. Facets |
| are reference counted, and locales can share facets. Therefore changing |
| the flags of a facet would have effects that are hard to predict. An |
| alternative design would be to implement the flags using <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ios_base</span><span class="special">::</span><span class="identifier">xalloc</span></code> and <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ios_base</span><span class="special">::</span><span class="identifier">iword</span></code>. |
| Then one could safely modify the flags, and one could define manipulators |
| that do so. However, for that to work with dynamically linked libraries, |
| a <code class="computeroutput"><span class="special">.</span><span class="identifier">cpp</span></code> |
| file would have to be added to the library. It was judged be more desirable |
| to have a headers only library, than to have mutable flags and manipulators. |
| </li> |
| <li> |
| The facet <code class="computeroutput"><span class="identifier">nonfinite_num_put</span></code> |
| throws an exception when the <code class="computeroutput"><span class="identifier">trap_infinity</span></code> |
| or <code class="computeroutput"><span class="identifier">trap_nan</span></code> flag is |
| set and an attempt is made to format infinity or NaN. It would be better |
| if the facet set the fail bit of the stream. However, facets derived |
| from <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">num_put</span></code> do not have access to the |
| stream state. |
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| <td align="right"><div class="copyright-footer">Copyright © 2006 , 2007, 2008, 2009, 2010 John Maddock, Paul A. Bristow, |
| Hubert Holin, Xiaogang Zhang, Bruno Lalande, Johan Råde, Gautam Sewani and |
| Thijs van den Berg<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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>) |
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