1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Annex: No Variadic Macros</title> 5<link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../index.html" title="Chapter 1. Boost.LocalFunction 1.0.0"> 8<link rel="up" href="../index.html" title="Chapter 1. Boost.LocalFunction 1.0.0"> 9<link rel="prev" href="alternatives.html" title="Annex: Alternatives"> 10<link rel="next" href="implementation.html" title="Annex: Implementation"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="alternatives.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="implementation.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 27<a name="boost_localfunction.no_variadic_macros"></a><a class="link" href="no_variadic_macros.html" title="Annex: No Variadic Macros">Annex: No Variadic 28 Macros</a> 29</h2></div></div></div> 30<p> 31 This section illustrates an alternative syntax for compilers without variadic 32 macro support. 33 </p> 34<h4> 35<a name="boost_localfunction.no_variadic_macros.h0"></a> 36 <span class="phrase"><a name="boost_localfunction.no_variadic_macros.sequence_syntax"></a></span><a class="link" href="no_variadic_macros.html#boost_localfunction.no_variadic_macros.sequence_syntax">Sequence Syntax</a> 37 </h4> 38<p> 39 Most modern compilers support <a href="http://en.wikipedia.org/wiki/Variadic_macro" target="_top">variaid 40 macros</a> (notably, these include GCC, MSVC, and all <a href="http://www.open-std.org/JTC1/SC22/WG21/" target="_top">C++11</a> 41 compilers). However, in the rare case that programmers need to use this library 42 on a compiler without variadic macros, this library also allows to specify 43 its macro parameters using a <a href="http://www.boost.org/libs/preprocessor" target="_top">Boost.Preprocessor</a> 44 sequence where tokens are separated by round parenthesis <code class="computeroutput"><span class="special">()</span></code>: 45 </p> 46<pre class="programlisting"><span class="special">(</span><span class="identifier">token1</span><span class="special">)</span> <span class="special">(</span><span class="identifier">token2</span><span class="special">)</span> <span class="special">...</span> <span class="comment">// All compilers.</span> 47</pre> 48<p> 49 Instead of the comma-separated list that we have seen so far which requires 50 variadic macros: 51 </p> 52<pre class="programlisting"><span class="identifier">token1</span><span class="special">,</span> <span class="identifier">token2</span><span class="special">,</span> <span class="special">...</span> <span class="comment">// Only compilers with varidic macros.</span> 53</pre> 54<p> 55 For example, the following syntax is accepted on all compilers with and without 56 variadic macros (see also <a href="../../../test/add_seq.cpp" target="_top"><code class="literal">add_seq.cpp</code></a>): 57 </p> 58<p> 59</p> 60<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">main</span><span class="special">(</span><span class="keyword">void</span><span class="special">)</span> <span class="special">{</span> 61 <span class="keyword">int</span> <span class="identifier">sum</span> <span class="special">=</span> <span class="number">0</span><span class="special">,</span> <span class="identifier">factor</span> <span class="special">=</span> <span class="number">10</span><span class="special">;</span> 62 63 <span class="keyword">void</span> <span class="identifier">BOOST_LOCAL_FUNCTION</span><span class="special">(</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">bind</span> <span class="identifier">factor</span><span class="special">)</span> <span class="special">(</span><span class="identifier">bind</span><span class="special">&</span> <span class="identifier">sum</span><span class="special">)</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">num</span><span class="special">)</span> <span class="special">)</span> <span class="special">{</span> 64 <span class="identifier">sum</span> <span class="special">+=</span> <span class="identifier">factor</span> <span class="special">*</span> <span class="identifier">num</span><span class="special">;</span> 65 <span class="special">}</span> <span class="identifier">BOOST_LOCAL_FUNCTION_NAME</span><span class="special">(</span><span class="identifier">add</span><span class="special">)</span> 66 67 <span class="identifier">add</span><span class="special">(</span><span class="number">1</span><span class="special">);</span> 68 <span class="keyword">int</span> <span class="identifier">nums</span><span class="special">[]</span> <span class="special">=</span> <span class="special">{</span><span class="number">2</span><span class="special">,</span> <span class="number">3</span><span class="special">};</span> 69 <span class="identifier">std</span><span class="special">::</span><span class="identifier">for_each</span><span class="special">(</span><span class="identifier">nums</span><span class="special">,</span> <span class="identifier">nums</span> <span class="special">+</span> <span class="number">2</span><span class="special">,</span> <span class="identifier">add</span><span class="special">);</span> 70 71 <span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">sum</span> <span class="special">==</span> <span class="number">60</span><span class="special">);</span> 72 <span class="keyword">return</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">report_errors</span><span class="special">();</span> 73<span class="special">}</span> 74</pre> 75<p> 76 </p> 77<p> 78 However, on compilers with variadic macros the comma-separated syntax we have 79 seen so far is preferred because more readable (see also <a href="../../../test/add.cpp" target="_top"><code class="literal">add.cpp</code></a>): 80 </p> 81<p> 82</p> 83<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">main</span><span class="special">(</span><span class="keyword">void</span><span class="special">)</span> <span class="special">{</span> <span class="comment">// Some local scope.</span> 84 <span class="keyword">int</span> <span class="identifier">sum</span> <span class="special">=</span> <span class="number">0</span><span class="special">,</span> <span class="identifier">factor</span> <span class="special">=</span> <span class="number">10</span><span class="special">;</span> <span class="comment">// Variables in scope to bind.</span> 85 86 <span class="keyword">void</span> <span class="identifier">BOOST_LOCAL_FUNCTION</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">bind</span> <span class="identifier">factor</span><span class="special">,</span> <span class="identifier">bind</span><span class="special">&</span> <span class="identifier">sum</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">num</span><span class="special">)</span> <span class="special">{</span> 87 <span class="identifier">sum</span> <span class="special">+=</span> <span class="identifier">factor</span> <span class="special">*</span> <span class="identifier">num</span><span class="special">;</span> 88 <span class="special">}</span> <span class="identifier">BOOST_LOCAL_FUNCTION_NAME</span><span class="special">(</span><span class="identifier">add</span><span class="special">)</span> 89 90 <span class="identifier">add</span><span class="special">(</span><span class="number">1</span><span class="special">);</span> <span class="comment">// Call the local function.</span> 91 <span class="keyword">int</span> <span class="identifier">nums</span><span class="special">[]</span> <span class="special">=</span> <span class="special">{</span><span class="number">2</span><span class="special">,</span> <span class="number">3</span><span class="special">};</span> 92 <span class="identifier">std</span><span class="special">::</span><span class="identifier">for_each</span><span class="special">(</span><span class="identifier">nums</span><span class="special">,</span> <span class="identifier">nums</span> <span class="special">+</span> <span class="number">2</span><span class="special">,</span> <span class="identifier">add</span><span class="special">);</span> <span class="comment">// Pass it to an algorithm.</span> 93 94 <span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">sum</span> <span class="special">==</span> <span class="number">60</span><span class="special">);</span> <span class="comment">// Assert final summation value.</span> 95 <span class="keyword">return</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">report_errors</span><span class="special">();</span> 96<span class="special">}</span> 97</pre> 98<p> 99 </p> 100<p> 101 Note that the same macros accept both syntaxes on compilers with variadic macros 102 and only the sequence syntax on compilers without variadic macros. Finally, 103 an empty local function parameter list is always specified using <code class="computeroutput"><span class="keyword">void</span></code> on compilers with and without variadic 104 macros: 105 </p> 106<p> 107</p> 108<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">BOOST_LOCAL_FUNCTION</span><span class="special">(</span><span class="keyword">void</span><span class="special">)</span> <span class="special">{</span> <span class="comment">// No parameter.</span> 109 <span class="keyword">return</span> <span class="number">10</span><span class="special">;</span> 110<span class="special">}</span> <span class="identifier">BOOST_LOCAL_FUNCTION_NAME</span><span class="special">(</span><span class="identifier">ten</span><span class="special">)</span> 111 112<span class="identifier">BOOST_TEST</span><span class="special">(</span><span class="identifier">ten</span><span class="special">()</span> <span class="special">==</span> <span class="number">10</span><span class="special">);</span> 113</pre> 114<p> 115 </p> 116<h4> 117<a name="boost_localfunction.no_variadic_macros.h1"></a> 118 <span class="phrase"><a name="boost_localfunction.no_variadic_macros.examples"></a></span><a class="link" href="no_variadic_macros.html#boost_localfunction.no_variadic_macros.examples">Examples</a> 119 </h4> 120<p> 121 For reference, the following is a list of most of the examples presented in 122 this documentation reprogrammed using the sequence syntax instead of the comma-separated 123 syntax (in alphabetic order): 124 </p> 125<div class="informaltable"><table class="table"> 126<colgroup><col></colgroup> 127<thead><tr><th> 128 <p> 129 Files 130 </p> 131 </th></tr></thead> 132<tbody> 133<tr><td> 134 <p> 135 <a href="../../../test/add_default_seq.cpp" target="_top"><code class="literal">add_default_seq.cpp</code></a> 136 </p> 137 </td></tr> 138<tr><td> 139 <p> 140 <a href="../../../test/add_except_seq.cpp" target="_top"><code class="literal">add_except_seq.cpp</code></a> 141 </p> 142 </td></tr> 143<tr><td> 144 <p> 145 <a href="../../../test/add_inline_seq.cpp" target="_top"><code class="literal">add_inline_seq.cpp</code></a> 146 </p> 147 </td></tr> 148<tr><td> 149 <p> 150 <a href="../../../test/add_params_only_seq.cpp" target="_top"><code class="literal">add_params_only_seq.cpp</code></a> 151 </p> 152 </td></tr> 153<tr><td> 154 <p> 155 <a href="../../../test/add_template_seq.cpp" target="_top"><code class="literal">add_template_seq.cpp</code></a> 156 </p> 157 </td></tr> 158<tr><td> 159 <p> 160 <a href="../../../test/add_this_seq.cpp" target="_top"><code class="literal">add_this_seq.cpp</code></a> 161 </p> 162 </td></tr> 163<tr><td> 164 <p> 165 <a href="../../../test/add_typed_seq.cpp" target="_top"><code class="literal">add_typed_seq.cpp</code></a> 166 </p> 167 </td></tr> 168<tr><td> 169 <p> 170 <a href="../../../test/add_with_default_seq.cpp" target="_top"><code class="literal">add_with_default_seq.cpp</code></a> 171 </p> 172 </td></tr> 173<tr><td> 174 <p> 175 <a href="../../../test/all_decl_seq.cpp" target="_top"><code class="literal">all_decl_seq.cpp</code></a> 176 </p> 177 </td></tr> 178<tr><td> 179 <p> 180 <a href="../../../test/factorial_seq.cpp" target="_top"><code class="literal">factorial_seq.cpp</code></a> 181 </p> 182 </td></tr> 183<tr><td> 184 <p> 185 <a href="../../../test/macro_commas_seq.cpp" target="_top"><code class="literal">macro_commas_seq.cpp</code></a> 186 </p> 187 </td></tr> 188<tr><td> 189 <p> 190 <a href="../../../test/nesting_seq.cpp" target="_top"><code class="literal">nesting_seq.cpp</code></a> 191 </p> 192 </td></tr> 193<tr><td> 194 <p> 195 <a href="../../../test/overload_seq.cpp" target="_top"><code class="literal">overload_seq.cpp</code></a> 196 </p> 197 </td></tr> 198<tr><td> 199 <p> 200 <a href="../../../test/return_assign_seq.cpp" target="_top"><code class="literal">return_assign_seq.cpp</code></a> 201 </p> 202 </td></tr> 203<tr><td> 204 <p> 205 <a href="../../../test/return_derivative_seq.cpp" target="_top"><code class="literal">return_derivative_seq.cpp</code></a> 206 </p> 207 </td></tr> 208<tr><td> 209 <p> 210 <a href="../../../test/return_inc_seq.cpp" target="_top"><code class="literal">return_inc_seq.cpp</code></a> 211 </p> 212 </td></tr> 213<tr><td> 214 <p> 215 <a href="../../../test/return_setget_seq.cpp" target="_top"><code class="literal">return_setget_seq.cpp</code></a> 216 </p> 217 </td></tr> 218<tr><td> 219 <p> 220 <a href="../../../test/return_this_seq.cpp" target="_top"><code class="literal">return_this_seq.cpp</code></a> 221 </p> 222 </td></tr> 223<tr><td> 224 <p> 225 <a href="../../../test/same_line_seq.cpp" target="_top"><code class="literal">same_line_seq.cpp</code></a> 226 </p> 227 </td></tr> 228<tr><td> 229 <p> 230 <a href="../../../test/transform_seq.cpp" target="_top"><code class="literal">transform_seq.cpp</code></a> 231 </p> 232 </td></tr> 233<tr><td> 234 <p> 235 <a href="../../../test/typeof_seq.cpp" target="_top"><code class="literal">typeof_seq.cpp</code></a> 236 </p> 237 </td></tr> 238<tr><td> 239 <p> 240 <a href="../../../test/typeof_template_seq.cpp" target="_top"><code class="literal">typeof_template_seq.cpp</code></a> 241 </p> 242 </td></tr> 243</tbody> 244</table></div> 245</div> 246<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 247<td align="left"></td> 248<td align="right"><div class="copyright-footer">Copyright © 2009-2012 Lorenzo 249 Caminiti<p> 250 Distributed under the Boost Software License, Version 1.0 (see accompanying 251 file LICENSE_1_0.txt or a copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 252 </p> 253</div></td> 254</tr></table> 255<hr> 256<div class="spirit-nav"> 257<a accesskey="p" href="alternatives.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.html"><img 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