1<?xml version='1.0'?> 2<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" 3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" 4[ ]> 5 6<chapter id="std.util" xreflabel="Utilities"> 7<?dbhtml filename="utilities.html"?> 8 9<chapterinfo> 10 <keywordset> 11 <keyword> 12 ISO C++ 13 </keyword> 14 <keyword> 15 library 16 </keyword> 17 </keywordset> 18</chapterinfo> 19 20<title> 21 Utilities 22 <indexterm><primary>Utilities</primary></indexterm> 23</title> 24 25<!-- Section 01 : Functors --> 26<section id="std.util.functors" xreflabel="Functors"> 27<?dbhtml filename="functors.html"?> 28 <title>Functors</title> 29 <para>If you don't know what functors are, you're not alone. Many people 30 get slightly the wrong idea. In the interest of not reinventing 31 the wheel, we will refer you to the introduction to the functor 32 concept written by SGI as chapter of their STL, in 33 <ulink url="http://www.sgi.com/tech/stl/functors.html">their 34 http://www.sgi.com/tech/stl/functors.html</ulink>. 35 </para> 36</section> 37 38<!-- Section 02 : Pairs --> 39<section id="std.util.pairs" xreflabel="Pairs"> 40<?dbhtml filename="pairs.html"?> 41 <title>Pairs</title> 42 <para>The <code>pair<T1,T2></code> is a simple and handy way to 43 carry around a pair of objects. One is of type T1, and another of 44 type T2; they may be the same type, but you don't get anything 45 extra if they are. The two members can be accessed directly, as 46 <code>.first</code> and <code>.second</code>. 47 </para> 48 <para>Construction is simple. The default ctor initializes each member 49 with its respective default ctor. The other simple ctor, 50 </para> 51 <programlisting> 52 pair (const T1& x, const T2& y); 53 </programlisting> 54 <para>does what you think it does, <code>first</code> getting <code>x</code> 55 and <code>second</code> getting <code>y</code>. 56 </para> 57 <para>There is a copy constructor, but it requires that your compiler 58 handle member function templates: 59 </para> 60 <programlisting> 61 template <class U, class V> pair (const pair<U,V>& p); 62 </programlisting> 63 <para>The compiler will convert as necessary from U to T1 and from 64 V to T2 in order to perform the respective initializations. 65 </para> 66 <para>The comparison operators are done for you. Equality 67 of two <code>pair<T1,T2></code>s is defined as both <code>first</code> 68 members comparing equal and both <code>second</code> members comparing 69 equal; this simply delegates responsibility to the respective 70 <code>operator==</code> functions (for types like MyClass) or builtin 71 comparisons (for types like int, char, etc). 72 </para> 73 <para> 74 The less-than operator is a bit odd the first time you see it. It 75 is defined as evaluating to: 76 </para> 77 <programlisting> 78 x.first < y.first || 79 ( !(y.first < x.first) && x.second < y.second ) 80 </programlisting> 81 <para>The other operators are not defined using the <code>rel_ops</code> 82 functions above, but their semantics are the same. 83 </para> 84 <para>Finally, there is a template function called <function>make_pair</function> 85 that takes two references-to-const objects and returns an 86 instance of a pair instantiated on their respective types: 87 </para> 88 <programlisting> 89 pair<int,MyClass> p = make_pair(4,myobject); 90 </programlisting> 91 92</section> 93 94<!-- Section 03 : Memory --> 95<section id="std.util.memory" xreflabel="Memory"> 96<?dbhtml filename="memory.html"?> 97 <title>Memory</title> 98 <para> 99 Memory contains three general areas. First, function and operator 100 calls via <function>new</function> and <function>delete</function> 101 operator or member function calls. Second, allocation via 102 <classname>allocator</classname>. And finally, smart pointer and 103 intelligent pointer abstractions. 104 </para> 105 106 <!-- Section 01 : allocator --> 107 <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" 108 parse="xml" href="allocator.xml"> 109 </xi:include> 110 111 <!-- Section 02 : auto_ptr --> 112 <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" 113 parse="xml" href="auto_ptr.xml"> 114 </xi:include> 115 116 <!-- Section 03 : shared_ptr --> 117 <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" 118 parse="xml" href="shared_ptr.xml"> 119 </xi:include> 120 121</section> 122 123<!-- Section 04 : Traits --> 124<section id="std.util.traits" xreflabel="Traits"> 125<?dbhtml filename="traits.html"?> 126 <title>Traits</title> 127 <para> 128 </para> 129</section> 130 131</chapter> 132