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<title>Design Rationale</title>
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<div class="section">
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="array.rationale"></a>Design Rationale</h2></div></div></div>
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<p>There was an important design tradeoff regarding the
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constructors: We could implement array as an "aggregate" (see
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Section 8.5.1, [dcl.init.aggr], of the C++ Standard). This would
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mean:
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
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<p class="simpara">An array can be initialized with a
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brace-enclosing, comma-separated list of initializers for the
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elements of the container, written in increasing subscript
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order:</p>
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<pre class="programlisting"><code class="computeroutput"><a class="link" href="../boost/array.html" title="Class template array">boost::array</a></code><int,4> a = { { 1, 2, 3 } };</pre>
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<p class="simpara">Note that if there are fewer elements in the
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initializer list, then each remaining element gets
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default-initialized (thus, it has a defined value).</p>
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</li></ul></div>
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<p>However, this approach has its drawbacks: <span class="bold"><strong> passing no initializer list means that the elements
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have an indetermined initial value</strong></span>, because the rule says
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that aggregates may have:
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
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<li class="listitem">No user-declared constructors.</li>
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<li class="listitem">No private or protected non-static data members.</li>
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<li class="listitem">No base classes.</li>
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<li class="listitem">No virtual functions.</li>
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</ul></div>
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<p>
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</p>
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<p>Nevertheless, The current implementation uses this approach.</p>
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<p>Note that for standard conforming compilers it is possible to
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use fewer braces (according to 8.5.1 (11) of the Standard). That is,
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you can initialize an array as follows:</p>
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<pre class="programlisting">
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<code class="computeroutput"><a class="link" href="../boost/array.html" title="Class template array">boost::array</a></code><int,4> a = { 1, 2, 3 };
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</pre>
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<p>I'd appreciate any constructive feedback. <span class="bold"><strong>Please note: I don't have time to read all boost
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mails. Thus, to make sure that feedback arrives to me, please send
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me a copy of each mail regarding this class.</strong></span></p>
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<p>The code is provided "as is" without expressed or implied
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warranty.</p>
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<td align="right"><div class="copyright-footer">Copyright © 2001-2004 Nicolai M. Josuttis<br>Copyright © 2012 Marshall Clow<p>Distributed under the Boost Software License, Version 1.0.
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(See accompanying file <code class="filename">LICENSE_1_0.txt</code> or copy at
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<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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