1<html> 2<head> 3<!-- Generated by the Spirit (http://spirit.sf.net) QuickDoc --> 4<title>Tuples</title> 5<link rel="stylesheet" href="theme/style.css" type="text/css"> 6<link rel="prev" href="inside_phoenix.html"> 7<link rel="next" href="actors_revisited.html"> 8</head> 9<body> 10<table width="100%" height="48" border="0" background="theme/bkd2.gif" cellspacing="2"> 11 <tr> 12 <td width="10"> 13 </td> 14 <td width="85%"> 15 <font size="6" face="Verdana, Arial, Helvetica, sans-serif"><b>Tuples</b></font> 16 </td> 17 <td width="112"><a href="http://spirit.sf.net"><img src="theme/spirit.gif" align="right" border="0"></a></td> 18 </tr> 19</table> 20<br> 21<table border="0"> 22 <tr> 23 <td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td> 24 <td width="30"><a href="inside_phoenix.html"><img src="theme/l_arr.gif" border="0"></a></td> 25 <td width="20"><a href="actors_revisited.html"><img src="theme/r_arr.gif" border="0"></a></td> 26 </tr> 27</table> 28<p> 29Tuples are the most basic infrastructure that the framework builds with. This sub-library provides a mechanism to bundle objects of arbitrary types in a single structure. Tuples hold heterogeneous types up to a predefined maximum.</p> 30<p> 31Only the most basic functionality needed are provided. This is a straight-forward and extremely lean and mean library. Unlike other recursive list-like tuple implementations, this tuple library implementation uses simple structs similar to std::pair with specialization for 0 to N tuple elements, where N is a predefined constant. There are only 4 tuple operations to learn:</p> 32<p> 331) Construction</p> 34<p> 35Here are examples on how to construct tuples:</p> 36<code><pre> 37 <span class=keyword>typedef </span><span class=identifier>tuple</span><span class=special><</span><span class=keyword>int</span><span class=special>, </span><span class=keyword>char</span><span class=special>> </span><span class=identifier>t1_t</span><span class=special>; 38 </span><span class=keyword>typedef </span><span class=identifier>tuple</span><span class=special><</span><span class=keyword>int</span><span class=special>, </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span><span class=special>, </span><span class=keyword>double</span><span class=special>> </span><span class=identifier>t2_t</span><span class=special>; 39 40 // </span><span class=keyword>this </span><span class=identifier>tuple </span><span class=identifier>has </span><span class=identifier>an </span><span class=keyword>int </span><span class=keyword>and </span><span class=keyword>char </span><span class=identifier>members 41 </span><span class=identifier>t1_t </span><span class=identifier>t1</span><span class=special>(</span><span class=number>3</span><span class=special>, </span><span class=literal>'c'</span><span class=special>); 42 43 // </span><span class=keyword>this </span><span class=identifier>tuple </span><span class=identifier>has </span><span class=identifier>an </span><span class=keyword>int</span><span class=special>, </span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string </span><span class=keyword>and </span><span class=keyword>double </span><span class=identifier>members 44 </span><span class=identifier>t2_t </span><span class=identifier>t2</span><span class=special>(</span><span class=number>3</span><span class=special>, </span><span class=string>"hello"</span><span class=special>, </span><span class=number>3.14</span><span class=special>); 45</span></pre></code> 46<p> 472) Member access</p> 48<p> 49A member in a tuple can be accessed using the tuple's operator by specifying the Nth tuple_index. Here are some examples:</p> 50<code><pre> 51 <span class=identifier>tuple_index</span><span class=special><</span><span class=number>0</span><span class=special>> </span><span class=identifier>ix0</span><span class=special>; // </span><span class=number>0</span><span class=identifier>th </span><span class=identifier>index </span><span class=special>== </span><span class=number>1</span><span class=identifier>st </span><span class=identifier>item 52 </span><span class=identifier>tuple_index</span><span class=special><</span><span class=number>1</span><span class=special>> </span><span class=identifier>ix1</span><span class=special>; // </span><span class=number>1</span><span class=identifier>st </span><span class=identifier>index </span><span class=special>== </span><span class=number>2</span><span class=identifier>nd </span><span class=identifier>item 53 </span><span class=identifier>tuple_index</span><span class=special><</span><span class=number>2</span><span class=special>> </span><span class=identifier>ix2</span><span class=special>; // </span><span class=number>2</span><span class=identifier>nd </span><span class=identifier>index </span><span class=special>== </span><span class=number>3</span><span class=identifier>rd </span><span class=identifier>item 54 55 </span><span class=comment>// Note zero based indexing. 0 = 1st item, 1 = 2nd item 56 57 </span><span class=identifier>t1</span><span class=special>[</span><span class=identifier>ix0</span><span class=special>] = </span><span class=number>33</span><span class=special>; // </span><span class=identifier>sets </span><span class=identifier>the </span><span class=keyword>int </span><span class=identifier>member </span><span class=identifier>of </span><span class=identifier>the </span><span class=identifier>tuple </span><span class=identifier>t1 58 </span><span class=identifier>t2</span><span class=special>[</span><span class=identifier>ix2</span><span class=special>] = </span><span class=number>6e6</span><span class=special>; // </span><span class=identifier>sets </span><span class=identifier>the </span><span class=keyword>double </span><span class=identifier>member </span><span class=identifier>of </span><span class=identifier>the </span><span class=identifier>tuple </span><span class=identifier>t2 59 </span><span class=identifier>t1</span><span class=special>[</span><span class=identifier>ix1</span><span class=special>] = </span><span class=literal>'a'</span><span class=special>; // </span><span class=identifier>sets </span><span class=identifier>the </span><span class=keyword>char </span><span class=identifier>member </span><span class=identifier>of </span><span class=identifier>the </span><span class=identifier>tuple </span><span class=identifier>t1 60</span></pre></code> 61<p> 62Access to out of bound indexes returns a nil_t value.</p> 63<p> 643) Member type inquiry</p> 65<p> 66The type of an individual member can be queried. Example:</p> 67<code><pre> 68 <span class=identifier>tuple_element</span><span class=special><</span><span class=number>1</span><span class=special>, </span><span class=identifier>t2_t</span><span class=special>>::</span><span class=identifier>type 69</span></pre></code> 70<p> 71Refers to the type of the second member (again note zero based indexing, hence 0 = 1st item, 1 = 2nd item) of the tuple.</p> 72<p> 73Access to out of bound indexes returns a nil_t type.</p> 74<p> 754) Tuple length</p> 76<p> 77The number of elements in a tuple can be queried. Example:</p> 78<code><pre> 79 <span class=keyword>int </span><span class=identifier>n </span><span class=special>= </span><span class=identifier>t1</span><span class=special>.</span><span class=identifier>length</span><span class=special>; 80</span></pre></code> 81<p> 82gets the number of elements in tuple t1.</p> 83<p> 84length is a static constant. Thus, TupleT::length also works. Example:</p> 85<code><pre> 86 <span class=keyword>int </span><span class=identifier>n </span><span class=special>= </span><span class=identifier>t1_t</span><span class=special>::</span><span class=identifier>length</span><span class=special>; 87</span></pre></code> 88<table border="0"> 89 <tr> 90 <td width="30"><a href="../index.html"><img src="theme/u_arr.gif" border="0"></a></td> 91 <td width="30"><a href="inside_phoenix.html"><img src="theme/l_arr.gif" border="0"></a></td> 92 <td width="20"><a href="actors_revisited.html"><img src="theme/r_arr.gif" border="0"></a></td> 93 </tr> 94</table> 95<br> 96<hr size="1"> 97<p class="copyright">Copyright © 2001-2002 Joel de Guzman<br> 98 <br> 99<font size="2">Use, modification and distribution is subject to the Boost Software 100 License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at 101 http://www.boost.org/LICENSE_1_0.txt) </font> </p> 102</body> 103</html> 104
