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Explanations about using tuples rather than arrays with variadic macro support.

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Edward Diener
2013-12-05 17:43:48 -05:00
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<html>
<head>
<title>arrays.html</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
<h4>Arrays</h4>
<div>
An <i>array</i> is a data structure consisting of a two-element <i>tuple</i>.&nbsp;
The first element is the number of elements in the <i>array</i>.&nbsp;
The second element is another <i>tuple</i> of the elements in the <i>array</i>.&nbsp;
For example,
</div>
<div class="code">
(<i>3</i>, (<i>a</i>, <i>b</i>, <i>c</i>))
</div>
<div>
...is an <i>array</i> of <i>3</i> elements--<i>a</i>, <i>b</i>, and <i>c</i>.
</div>
<div>
The primary strength of <i>arrays</i> is that they store their own size.&nbsp;
Because of this, access to elements does not require the size.&nbsp;
It only requires that an element exists at a certain index.
</div>
<div>
This allows macro parameters to be variable in size and allows data states to change
size without the user explicitly keeping track of the size independently.
</div>
<div>
Elements of an <i>array</i> can be extracted with <b>BOOST_PP_ARRAY_ELEM</b>,
an <i>array's</i> size can be extracted with <b>BOOST_PP_ARRAY_SIZE</b>, and
an <i>array</i> can be converted to the more primitive <i>tuple</i> data structure
with <b>BOOST_PP_ARRAY_DATA</b>.
</div>
<h4>Primitives</h4>
<ul>
<li><a href="../ref/array_data.html">BOOST_PP_ARRAY_DATA</a></li>
<li><a href="../ref/array_elem.html">BOOST_PP_ARRAY_ELEM</a></li>
<li><a href="../ref/array_size.html">BOOST_PP_ARRAY_SIZE</a></li>
</ul>
<hr size="1">
<div style="margin-left: 0px;">
<i><EFBFBD> Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
</br><i><EFBFBD> Copyright Paul Mensonides 2002</i>
</div>
<div style="margin-left: 0px;">
<p><small>Distributed under the Boost Software License, Version 1.0. (See
accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
copy at <a href=
"http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
</div>
</body>
<head>
<title>arrays.html</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
<h4>Arrays</h4>
<div> An <i>array</i> is a data structure consisting of a two-element <i>tuple</i>.&nbsp;
The first element is the number of elements in the <i>array</i>.&nbsp;
The second element is another <i>tuple</i> of the elements in the <i>array</i>.&nbsp;
For example, </div>
<div class="code"> (<i>3</i>, (<i>a</i>, <i>b</i>, <i>c</i>)) </div>
<div> ...is an <i>array</i> of <i>3</i> elements--<i>a</i>, <i>b</i>, and
<i>c</i>. </div>
<div> The primary strength of <i>arrays</i> is that they store their own
size.&nbsp; Because of this, access to elements does not require the
size.&nbsp; It only requires that an element exists at a certain index. </div>
<div> This allows macro parameters to be variable in size and allows data
states to change size without the user explicitly keeping track of the
size independently.</div>
<div>With variadic macro support a <i>tuple </i>has all of the
functionality as an <i>array</i>, knows its own size, and is easier
syntactically to use. Because of that an <i>array</i> should be used, as
opposed to a <i>tuple</i>, only if your compiler does not support
variadic macros.<br>
<br>
Elements of an <i>array</i> can be extracted with <b>BOOST_PP_ARRAY_ELEM</b>,
an <i>array's</i> size can be extracted with <b>BOOST_PP_ARRAY_SIZE</b>,
and an <i>array</i> can be converted to the more primitive <i>tuple</i>
data structure with <b>BOOST_PP_ARRAY_DATA</b>. </div>
<h4>Primitives</h4>
<ul>
<li><a href="../ref/array_data.html">BOOST_PP_ARRAY_DATA</a></li>
<li><a href="../ref/array_elem.html">BOOST_PP_ARRAY_ELEM</a></li>
<li><a href="../ref/array_size.html">BOOST_PP_ARRAY_SIZE</a></li>
</ul>
<hr size="1">
<div style="margin-left: 0px;"> <i><EFBFBD> Copyright <a href="http://www.housemarque.com"
target="_top">Housemarque Oy</a> 2002</i> <br>
<i><EFBFBD> Copyright Paul Mensonides 2002</i> </div>
<div style="margin-left: 0px;">
<p><small>Distributed under the Boost Software License, Version 1.0. (See
accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
</div>
</body>
</html>