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| <div class="titlepage"><div><div><h2 class="title" style="clear: both"> |
| <a name="foreach.history_and_acknowledgements"></a><a class="link" href="history_and_acknowledgements.html" title="History and Acknowledgements">History and Acknowledgements</a> |
| </h2></div></div></div> |
| <a name="foreach.history_and_acknowledgements.history"></a><h3> |
| <a name="id1263309"></a> |
| <a class="link" href="history_and_acknowledgements.html#foreach.history_and_acknowledgements.history">History</a> |
| </h3> |
| <p> |
| The ideas for <code class="literal">BOOST_FOREACH</code> began life in the Visual C++ |
| group at Microsoft during the early phases of the design for C++/CLI. Whether |
| to add a dedicated "foreach" looping construct to the language was |
| an open question at the time. As a mental exercise, Anson Tsao sent around |
| some proof-of-concept code which demonstrated that a pure library solution |
| might be possible. The code was written in the proposed C++/CLI dialect of |
| the time, for which there was no compiler as of yet. I was intrigued by the |
| possibility, and I ported his code to Managed C++ and got it working. We worked |
| together to refine the idea and eventually published an article about it in |
| the November 2003 issue of the <a href="http://www.cuj.com" target="_top">CUJ</a>. |
| </p> |
| <p> |
| After leaving Microsoft, I revisited the idea of a looping construct. I reimplemented |
| the macro from scratch in standard C++, corrected some shortcomings of the |
| CUJ version and rechristened it <code class="literal">BOOST_FOREACH</code>. In October |
| of 2003 I began a discussion about it on the Boost developers list, where it |
| met with a luke-warm reception. I dropped the issue until December 2004, when |
| I reimplemented <code class="literal">BOOST_FOREACH</code> yet again. The new version |
| only evaluated its sequence expression once and correctly handled both lvalue |
| and rvalue sequence expressions. It was built on top of the recently accepted |
| <a href="../../../libs/range/index.html" target="_top">Boost.Range</a> library, which |
| increased its portability. This was the version that, on Dec. 12 2004, I finally |
| submitted to Boost for review. It was accepted into Boost on May 5, 2005. |
| </p> |
| <a name="foreach.history_and_acknowledgements.acknowledgements"></a><h3> |
| <a name="id1263379"></a> |
| <a class="link" href="history_and_acknowledgements.html#foreach.history_and_acknowledgements.acknowledgements">Acknowledgements</a> |
| </h3> |
| <p> |
| Thanks go out to Anson Tsao of Microsoft for coming up with the idea and demonstrating |
| its feasibility. I would also like to thank <a href="http://boost.org/people/thorsten_ottosen.html" target="_top">Thorsten |
| Ottosen</a> for the <a href="../../../libs/range/index.html" target="_top">Boost.Range</a> |
| library, on which the current version of <code class="literal">BOOST_FOREACH</code> is |
| built. Finally, I'd like to thank Russell Hind, Alisdair Meredith and Stefan |
| Slapeta for their help porting to various compilers. |
| </p> |
| <a name="foreach.history_and_acknowledgements.further_reading"></a><h3> |
| <a name="id1263429"></a> |
| <a class="link" href="history_and_acknowledgements.html#foreach.history_and_acknowledgements.further_reading">Further |
| Reading</a> |
| </h3> |
| <p> |
| For more information about how <code class="literal">BOOST_FOREACH</code> works, you |
| may refer to the article <a href="http://www.artima.com/cppsource/foreach.html" target="_top"><span class="quote">“<span class="quote">Conditional |
| Love</span>”</span></a> at <a href="http://www.artima.com/cppsource/" target="_top">The C++ |
| Source</a>. |
| </p> |
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| <td align="right"><div class="copyright-footer">Copyright © 2004 Eric Niebler<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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