Planet
navi homePPSaboutscreenshotsdownloaddevelopmentforum

source: downloads/boost_1_34_1/libs/mpl/doc/refmanual/assert-msg.html @ 29

Last change on this file since 29 was 29, checked in by landauf, 17 years ago

updated boost from 1_33_1 to 1_34_1
File size: 9.5 KB
Line 
1<?xml version="1.0" encoding="utf-8" ?>
2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
4<!-- Copyright Aleksey Gurtovoy 2006. Distributed under the Boost -->
5<!-- Software License, Version 1.0. (See accompanying -->
6<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
7<head>
8<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
9<meta name="generator" content="Docutils 0.3.6: http://docutils.sourceforge.net/" />
10<title>The MPL Reference Manual: BOOST_MPL_ASSERT_MSG</title>
11<link rel="stylesheet" href="../style.css" type="text/css" />
12</head>
13<body class="docframe refmanual">
14<table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./assert.html" class="navigation-link">Prev</a>&nbsp;<a href="./assert-not.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./assert.html" class="navigation-link">Back</a>&nbsp;<a href="./assert-not.html" class="navigation-link">Along</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./asserts.html" class="navigation-link">Up</a>&nbsp;<a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td>
15<td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./macros.html" class="navigation-link">Macros</a> / <a href="./asserts.html" class="navigation-link">Asserts</a> / <a href="./assert-msg.html" class="navigation-link">BOOST_MPL_ASSERT_MSG</a></td>
16</tr></table><div class="header-separator"></div>
17<div class="section" id="assert-msg">
18<h1><a class="toc-backref" href="./asserts.html#id512" name="assert-msg">BOOST_MPL_ASSERT_MSG</a></h1>
19<div class="section" id="asserts-assert-synopsis">
20<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
21<pre class="literal-block">
22#define <a href="./assert-msg.html" class="identifier">BOOST_MPL_ASSERT_MSG</a>( condition, message, types ) \
23    <em>unspecified token sequence</em> \
24/**/
25</pre>
26</div>
27<div class="section" id="asserts-assert-description">
28<h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
29<p>Generates a compilation error with an embedded custom message when the condition
30doesn't hold.</p>
31</div>
32<div class="section" id="asserts-assert-header">
33<h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
34<pre class="literal-block">
35#include &lt;<a href="../../../../boost/mpl/assert.hpp" class="header">boost/mpl/assert.hpp</a>&gt;
36</pre>
37</div>
38<div class="section" id="asserts-assert-parameters">
39<h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
40<table border="1" class="table">
41<colgroup>
42<col width="15%" />
43<col width="36%" />
44<col width="48%" />
45</colgroup>
46<thead valign="bottom">
47<tr><th>Parameter</th>
48<th>Requirement</th>
49<th>Description</th>
50</tr>
51</thead>
52<tbody valign="top">
53<tr><td><tt class="literal"><span class="pre">condition</span></tt></td>
54<td>An integral constant expression</td>
55<td>A condition to be asserted.</td>
56</tr>
57<tr><td><tt class="literal"><span class="pre">message</span></tt></td>
58<td>A legal identifier token</td>
59<td>A custom message in a form of a legal C++
60identifier token.</td>
61</tr>
62<tr><td><tt class="literal"><span class="pre">types</span></tt></td>
63<td>A legal function parameter list</td>
64<td>A parenthized list of types to be displayed
65in the error message.</td>
66</tr>
67</tbody>
68</table>
69</div>
70<div class="section" id="asserts-assert-expression-semantics">
71<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
72<p>For any integral constant expression <tt class="literal"><span class="pre">expr</span></tt>, legal C++ identifier <tt class="literal"><span class="pre">message</span></tt>, and
73arbitrary types <tt class="literal"><span class="pre">t1</span></tt>, <tt class="literal"><span class="pre">t2</span></tt>,... <tt class="literal"><span class="pre">tn</span></tt>:</p>
74<pre class="literal-block">
75<a href="./assert-msg.html" class="identifier">BOOST_MPL_ASSERT_MSG</a>( expr, message, (t1, t2,... tn) );
76</pre>
77<table class="field-list" frame="void" rules="none">
78<col class="field-name" />
79<col class="field-body" />
80<tbody valign="top">
81<tr class="field"><th class="field-name">Return type:</th><td class="field-body">None.</td>
82</tr>
83<tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><tt class="literal"><span class="pre">t1</span></tt>, <tt class="literal"><span class="pre">t2</span></tt>,... <tt class="literal"><span class="pre">tn</span></tt> are non-<tt class="literal"><span class="pre">void</span></tt>.</td>
84</tr>
85<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Generates a compilation error if <tt class="literal"><span class="pre">expr::value</span> <span class="pre">!=</span> <span class="pre">true</span></tt>, otherwise
86has no effect.</p>
87<p>When possible within the compiler's diagnostic capabilities,
88the error message will include the <tt class="literal"><span class="pre">message</span></tt> identifier and the parenthized
89list of <tt class="literal"><span class="pre">t1</span></tt>, <tt class="literal"><span class="pre">t2</span></tt>,... <tt class="literal"><span class="pre">tn</span></tt> types, and have a general form of:</p>
90<pre class="last literal-block">
91<em>...</em> ************( <em>...</em>::message )************)(t1, t2,... tn) <em>...</em>
92</pre>
93</td>
94</tr>
95</tbody>
96</table>
97<pre class="literal-block">
98<a href="./assert-msg.html" class="identifier">BOOST_MPL_ASSERT_MSG</a>( expr, message, (types&lt;t1, t2,... tn&gt;) );
99</pre>
100<table class="field-list" frame="void" rules="none">
101<col class="field-name" />
102<col class="field-body" />
103<tbody valign="top">
104<tr class="field"><th class="field-name">Return type:</th><td class="field-body">None.</td>
105</tr>
106<tr class="field"><th class="field-name">Precondition:</th><td class="field-body">None.</td>
107</tr>
108<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Generates a compilation error if <tt class="literal"><span class="pre">expr::value</span> <span class="pre">!=</span> <span class="pre">true</span></tt>, otherwise
109has no effect.</p>
110<p>When possible within the compiler's diagnostics capabilities,
111the error message will include the <tt class="literal"><span class="pre">message</span></tt> identifier and the list of
112<tt class="literal"><span class="pre">t1</span></tt>, <tt class="literal"><span class="pre">t2</span></tt>,... <tt class="literal"><span class="pre">tn</span></tt> types, and have a general form of:</p>
113<pre class="last literal-block">
114<em>...</em> ************( <em>...</em>::message )************)(types&lt;t1, t2,... tn&gt;) <em>...</em>
115</pre>
116</td>
117</tr>
118</tbody>
119</table>
120</div>
121<div class="section" id="asserts-assert-example">
122<h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
123<pre class="literal-block">
124template&lt; typename T &gt; struct my
125{
126    // ...
127    <a href="./assert-msg.html" class="identifier">BOOST_MPL_ASSERT_MSG</a>(
128          is_integral&lt;T&gt;::value
129        , NON_INTEGRAL_TYPES_ARE_NOT_ALLOWED
130        , (T)
131        );
132};
133
134my&lt;void*&gt; test;
135
136// In instantiation of `my&lt;void*&gt;':
137//   instantiated from here
138// conversion from `
139//   mpl_::failed************(my&lt;void*&gt;::
140//   NON_INTEGRAL_TYPES_ARE_NOT_ALLOWED::************)(void*)
141//   ' to non-scalar type `mpl_::assert&lt;false&gt;' requested
142</pre>
143</div>
144<div class="section" id="asserts-assert-see-also">
145<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
146<p><a class="reference" href="./asserts.html">Asserts</a>, <a class="refentry reference" href="./assert.html"><tt class="refentry literal"><span class="pre">BOOST_MPL_ASSERT</span></tt></a>, <a class="refentry reference" href="./assert-not.html"><tt class="refentry literal"><span class="pre">BOOST_MPL_ASSERT_NOT</span></tt></a>, <a class="refentry reference" href="./assert-relation.html"><tt class="refentry literal"><span class="pre">BOOST_MPL_ASSERT_RELATION</span></tt></a></p>
147<!-- modtime: November 10, 2004 04:45:24 +0000 -->
148<!-- Macros/Asserts//BOOST_MPL_ASSERT_NOT -->
149</div>
150</div>
151
152<div class="footer-separator"></div>
153<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./assert.html" class="navigation-link">Prev</a>&nbsp;<a href="./assert-not.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./assert.html" class="navigation-link">Back</a>&nbsp;<a href="./assert-not.html" class="navigation-link">Along</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./asserts.html" class="navigation-link">Up</a>&nbsp;<a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td>
154</tr></table></body>
155</html>
Note: See TracBrowser for help on using the repository browser.