1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<HTML> 3<HEAD> 4 <TITLE>Class Template chain</TITLE> 5 <LINK REL="stylesheet" HREF="../../../../boost.css"> 6 <LINK REL="stylesheet" HREF="../theme/iostreams.css"> 7</HEAD> 8<BODY> 9 10<!-- Begin Banner --> 11 12 <H1 CLASS="title">Function Template <CODE>compose</CODE></H1> 13 <HR CLASS="banner"> 14 15<!-- End Banner --> 16 17<DL class="page-index"> 18 <DT><A href="#description">Description</A></DT> 19 <DT><A href="#headers">Headers</A></DT> 20 <DT><A href="#reference">Reference</A></DT> 21</DL> 22 23<HR> 24 25<A NAME="description"></A> 26<H2>Description</H2> 27 28<P> 29 Given a Filter <CODE>f</CODE> and a Device <CODE>d</CODE>, we may construct a device <CODE>c</CODE> whose member functions are implemented by invoking the fundamental i/o operations <A HREF='../functions/read.html'><CODE>read</CODE></A>, <A HREF='../functions/write.html'><CODE>write</CODE></A>, <I>etc.</I> with <CODE>f</CODE> as the first argument and <CODE>d</CODE> as the second. Similarly, if we are given two filters <CODE>f1</CODE> and <CODE>f2</CODE>, we may construct a third filter <CODE>f3</CODE> whose member function templates are implemented by invoking the fundamental i/o operations <A HREF='../functions/read.html'><CODE>read</CODE></A>, <A HREF='../functions/write.html'><CODE>write</CODE></A>, <I>etc.</I>, with first argument equal to <CODE>f1</CODE> and second argument equal to the result of composing <CODE>f2</CODE> with the provided Device. 30</P> 31 32<P> 33 The function template <A HREF='#composite'><CODE>composite</CODE></A> represents a Filter or Device which has been constructed in the above manner. The function template <A HREF='#compose'><CODE>compose</CODE></A> is an <A HREF='http://www.boost.org/more/generic_programming.html#object_generator' TARGET='_top'>object generator</A> which given a pair of components returns an appropriate instance of <CODE>composite</CODE>. 34</P> 35 36<P> 37 The <A HREF='../guide/modes.html'>mode</A> of a <CODE>composite</CODE> is defined to provide a maximal subset of the common functionality of the two components. A <CODE>composite</CODE> is <A HREF='../concepts/closable.html'>Closable</A>, <A HREF='../concepts/flushable.html'>Flushable</A>, <A HREF='../concepts/localizable.html'>Localizable</A> and <A HREF='../concepts/optimally_buffered.html'>OptimallyBuffered</A>. 38</P> 39 40<A NAME="headers"></A> 41<H2>Headers</H2> 42 43<DL class="page-index"> 44 <DT><A CLASS="header" HREF="../../../../boost/iostreams/compose.hpp"><CODE><boost/iostreams/compose.hpp></CODE></A></DT> 45</DL> 46 47<A NAME="reference"></A> 48<H2>Reference</H2> 49 50<A NAME="synopsis"></A> 51<H4>Synopsis</H4> 52 53<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { 54 55<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#composite_template_params">Filter</A>, <SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#composite_template_params">FilterOrDevice</A>> 56<SPAN CLASS='keyword'>class</SPAN> <A CLASS='documented' HREF='#composite'>composite</A> { 57<SPAN CLASS='keyword'>public:</SPAN> 58 <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='keyword'>typename</SPAN> <A CLASS='documented' HREF='../guide/traits.html#char_type'>char_type_of</A><Filter>::type char_type; 59 <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>implementation-defined</SPAN> mode; 60 61 <A CLASS='documented' HREF='#composite_ctor'>composite</A>(<SPAN CLASS='keyword'>const</SPAN> Filter& first, [<SPAN CLASS='keyword'>const</SPAN>] FilterOrDevice& second); 62 63 <SPAN CLASS='comment'>// Filter or Device member functions</SPAN> 64}; 65 66<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#compose_template_params">Filter</A>, <SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#compose_template_params">FilterOrDevice</A>> 67<A CLASS='documented' HREF='#composite'>composite</A><Filter, FilterOrDevice> 68<A CLASS='documented' HREF='#compose'>compose</A>(<SPAN CLASS='keyword'>const</SPAN> Filter& first, [<SPAN CLASS='keyword'>const</SPAN>] FilterOrDevice& second); 69 70} } // End namespace boost::io</PRE> 71 72<A NAME="composite"></A> 73<H2>Class Template <CODE>composite</CODE></H2> 74 75<A NAME="composite_template_params"></A> 76<H4>Template parameters</H4> 77 78<TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> 79<TR> 80 <TR> 81 <TD VALIGN="top"><I>Filter</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 82 <TD>A model of <A HREF='../concepts/filter.html'>Filter</A></TD> 83 </TR> 84 <TR> 85 <TD VALIGN="top"><I>FilterOrDevice</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 86 <TD>A model of <A HREF='../concepts/filter.html'>Filter</A> or <A HREF='../concepts/device.html'>Device</A></TD> 87 </TR> 88</TABLE> 89 90<A NAME="composite_ctor"></A> 91<H4><CODE>composite::composite</CODE></H4> 92 93<PRE CLASS="broken_ie"> composite(<SPAN CLASS='keyword'>const</SPAN> Filter& first, [<SPAN CLASS='keyword'>const</SPAN>] FilterOrDevice& second);</PRE> 94 95<P> 96 Constructs an instance of <CODE>composite</CODE> based on the given components. If <CODE>FilterOrDevice</CODE> is a stream or stream buffer type, the second parameter is a non-<CODE>const</CODE> reference; otherwise it is a <CODE>const</CODE> reference. 97</P> 98 99<A NAME="compose"></A> 100<H2>Function Template <CODE>compose</CODE></H2> 101 102<PRE CLASS="broken_ie"> composite(<SPAN CLASS='keyword'>const</SPAN> Filter& first, [<SPAN CLASS='keyword'>const</SPAN>] FilterOrDevice& second);</PRE> 103 104<A NAME="compose_template_params"></A> 105<H4>Template parameters</H4> 106 107<TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> 108<TR> 109 <TR> 110 <TD VALIGN="top"><I>Filter</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 111 <TD>A model of <A HREF='../concepts/filter.html'>Filter</A></TD> 112 </TR> 113 <TR> 114 <TD VALIGN="top"><I>FilterOrDevice</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 115 <TD>A model of <A HREF='../concepts/filter.html'>Filter</A> or <A HREF='../concepts/device.html'>Device</A></TD> 116 </TR> 117</TABLE> 118 119<P> 120 Returns an instance of an appropriate specialization of <CODE>composite</CODE> constructed from the given components. If <CODE>FilterOrDevice</CODE> is a stream or stream buffer type, the second parameter is a non-<CODE>const</CODE> reference; otherwise it is a <CODE>const</CODE> reference. 121</P> 122 123<!-- Begin Footer --> 124 125<HR> 126 127<P CLASS="copyright">© Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>© Copyright 2004-2007 <a href="https://www.boost.org/users/people/jonathan_turkanis.html" target="_top">Jonathan Turkanis</a></P> 128<P CLASS="copyright"> 129 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">http://www.boost.org/LICENSE_1_0.txt</A>) 130</P> 131 132<!-- End Footer --> 133 134</BODY> 135