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7 <title>The MPL Reference Manual: BOOST_MPL_ASSERT
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14 <div class=
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15 <h1><a class=
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"./asserts.html#id1588">BOOST_MPL_ASSERT
</a></h1>
16 <div class=
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17 <h3><a class=
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</a></h3>
18 <pre class=
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19 #define
<a href=
"./assert.html" class=
"identifier">BOOST_MPL_ASSERT
</a>( pred ) \
20 <em>unspecified token sequence
</em> \
24 <div class=
"section" id=
"id1288">
25 <h3><a class=
"subsection-title" href=
"#description" name=
"description">Description
</a></h3>
26 <p>Generates a compilation error when the predicate
<tt class=
"literal"><span class=
"pre">pred
</span></tt> holds false.
</p>
28 <div class=
"section" id=
"id1289">
29 <h3><a class=
"subsection-title" href=
"#header" name=
"header">Header
</a></h3>
30 <pre class=
"literal-block">
31 #include
<<a href=
"../../../../boost/mpl/assert.hpp" class=
"header">boost/mpl/assert.hpp
</a>>
34 <div class=
"section" id=
"id1290">
35 <h3><a class=
"subsection-title" href=
"#parameters" name=
"parameters">Parameters
</a></h3>
36 <table border=
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42 <thead valign=
"bottom">
43 <tr><th class=
"head">Parameter
</th>
44 <th class=
"head">Requirement
</th>
45 <th class=
"head">Description
</th>
49 <tr><td><tt class=
"literal"><span class=
"pre">pred
</span></tt></td>
50 <td>Boolean nullary
<a class=
"reference internal" href=
"./metafunction.html">Metafunction
</a></td>
51 <td>A predicate to be asserted.
</td>
56 <div class=
"section" id=
"id1291">
57 <h3><a class=
"subsection-title" href=
"#expression-semantics" name=
"expression-semantics">Expression semantics
</a></h3>
58 <p>For any boolean nullary
<a class=
"reference internal" href=
"./metafunction.html">Metafunction
</a> <tt class=
"literal"><span class=
"pre">pred
</span></tt>:
</p>
59 <pre class=
"literal-block">
60 <a href=
"./assert.html" class=
"identifier">BOOST_MPL_ASSERT
</a>(( pred ));
62 <table class=
"docutils field-list" frame=
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63 <col class=
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64 <col class=
"field-body" />
66 <tr class=
"field"><th class=
"field-name">Return type:
</th><td class=
"field-body"><p class=
"first">None.
</p>
69 <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">pred::type::value
</span> <span class=
"pre">!=
</span> <span class=
"pre">true
</span></tt>, otherwise
70 has no effect. Note that double parentheses are required even if no commas
71 appear in the condition.
</p>
72 <p>When possible within the compiler's diagnostic capabilities,
73 the error message will include the predicate's full type name, and have a
75 <pre class=
"last literal-block">
76 <em>...
</em> ************ pred::************
<em>...
</em>
83 <div class=
"section" id=
"id1292">
84 <h3><a class=
"subsection-title" href=
"#example" name=
"example">Example
</a></h3>
85 <pre class=
"literal-block">
86 template
< typename T, typename U
> struct my
89 <a href=
"./assert.html" class=
"identifier">BOOST_MPL_ASSERT
</a>(( is_same
< T,U
> ));
92 my
<void*,char*
> test;
94 // In instantiation of `my
<void, char*
>':
95 // instantiated from here
97 // mpl_::failed************boost::is_same
<void, char*
>::************' to
98 // non-scalar type `mpl_::assert
<false
>' requested
101 <div class=
"section" id=
"id1293">
102 <h3><a class=
"subsection-title" href=
"#see-also" name=
"see-also">See also
</a></h3>
103 <p><a class=
"reference internal" href=
"./asserts.html">Asserts
</a>,
<a class=
"reference internal" href=
"./assert-not.html">BOOST_MPL_ASSERT_NOT
</a>,
<a class=
"reference internal" href=
"./assert-msg.html">BOOST_MPL_ASSERT_MSG
</a>,
<a class=
"reference internal" href=
"./assert-relation.html">BOOST_MPL_ASSERT_RELATION
</a></p>
104 <!-- Macros/Asserts//BOOST_MPL_ASSERT_MSG -->
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110 <td><div class=
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"copyright">Copyright ©
2001-
2009 Aleksey Gurtovoy and David Abrahams
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111 Distributed under the Boost Software License, Version
1.0. (See accompanying
112 file LICENSE_1_0.txt or copy at
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"http://www.boost.org/LICENSE_1_0.txt" target=
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