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< title > The MPL Reference Manual: BOOST_MPL_ASSERT_MSG< / title >
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< 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 >
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< div class = "section" id = "boost-mpl-assert-msg" >
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< h1 > < a class = "toc-backref" href = "./asserts.html#id1589" > BOOST_MPL_ASSERT_MSG< / a > < / h1 >
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< div class = "section" id = "id1294" >
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< h3 > < a class = "subsection-title" href = "#synopsis" name = "synopsis" > Synopsis< / a > < / h3 >
< pre class = "literal-block" >
#define < a href = "./assert-msg.html" class = "identifier" > BOOST_MPL_ASSERT_MSG< / a > ( condition, message, types ) \
< em > unspecified token sequence< / em > \
/**/
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< div class = "section" id = "id1295" >
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< h3 > < a class = "subsection-title" href = "#description" name = "description" > Description< / a > < / h3 >
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< p > Generates a compilation error with an embedded custom message when the condition
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doesn't hold.< / p >
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< div class = "section" id = "id1296" >
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< h3 > < a class = "subsection-title" href = "#header" name = "header" > Header< / a > < / h3 >
< pre class = "literal-block" >
#include < < a href = "../../../../boost/mpl/assert.hpp" class = "header" > boost/mpl/assert.hpp< / a > >
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< div class = "section" id = "id1297" >
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< h3 > < a class = "subsection-title" href = "#parameters" name = "parameters" > Parameters< / a > < / h3 >
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< table border = "1" class = "docutils table" >
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< tr > < th class = "head" > Parameter< / th >
< th class = "head" > Requirement< / th >
< th class = "head" > Description< / th >
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< / tr >
< / thead >
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< tr > < td > < tt class = "literal" > < span class = "pre" > condition< / span > < / tt > < / td >
< td > An integral constant expression< / td >
< td > A condition to be asserted.< / td >
< / tr >
< tr > < td > < tt class = "literal" > < span class = "pre" > message< / span > < / tt > < / td >
< td > A legal identifier token< / td >
< td > A custom message in a form of a legal C++
identifier token.< / td >
< / tr >
< tr > < td > < tt class = "literal" > < span class = "pre" > types< / span > < / tt > < / td >
< td > A legal function parameter list< / td >
< td > A parenthized list of types to be displayed
in the error message.< / td >
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< / tbody >
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< div class = "section" id = "id1298" >
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< h3 > < a class = "subsection-title" href = "#expression-semantics" name = "expression-semantics" > Expression semantics< / a > < / h3 >
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< 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
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arbitrary 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 >
< pre class = "literal-block" >
< a href = "./assert-msg.html" class = "identifier" > BOOST_MPL_ASSERT_MSG< / a > ( expr, message, (t1, t2,... tn) );
< / pre >
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< table class = "docutils field-list" frame = "void" rules = "none" >
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< col class = "field-name" / >
< col class = "field-body" / >
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< tr class = "field" > < th class = "field-name" > Return type:< / th > < td class = "field-body" > < p class = "first" > None.< / p >
< / td >
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< / tr >
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< tr class = "field" > < th class = "field-name" > Precondition:< / th > < td class = "field-body" > < p class = "first" > < 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 > .< / p >
< / td >
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< / tr >
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< 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< / span > < span class = "pre" > !=< / span > < span class = "pre" > true< / span > < / tt > , otherwise
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has no effect.< / p >
< p > When possible within the compiler's diagnostic capabilities,
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the error message will include the < tt class = "literal" > < span class = "pre" > message< / span > < / tt > identifier and the parenthized
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list 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 >
< pre class = "last literal-block" >
< em > ...< / em > ************( < em > ...< / em > ::message )************)(t1, t2,... tn) < em > ...< / em >
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< / tr >
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< pre class = "literal-block" >
< a href = "./assert-msg.html" class = "identifier" > BOOST_MPL_ASSERT_MSG< / a > ( expr, message, (types< t1, t2,... tn> ) );
< / pre >
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< table class = "docutils field-list" frame = "void" rules = "none" >
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< col class = "field-name" / >
< col class = "field-body" / >
< tbody valign = "top" >
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< tr class = "field" > < th class = "field-name" > Return type:< / th > < td class = "field-body" > < p class = "first" > None.< / p >
< / td >
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< / tr >
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< tr class = "field" > < th class = "field-name" > Precondition:< / th > < td class = "field-body" > < p class = "first" > None.< / p >
< / td >
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< / tr >
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< 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< / span > < span class = "pre" > !=< / span > < span class = "pre" > true< / span > < / tt > , otherwise
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has no effect.< / p >
< p > When possible within the compiler's diagnostics capabilities,
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the error message will include the < tt class = "literal" > < span class = "pre" > message< / span > < / tt > identifier and the list of
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< 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 >
< pre class = "last literal-block" >
< em > ...< / em > ************( < em > ...< / em > ::message )************)(types< t1, t2,... tn> ) < em > ...< / em >
< / pre >
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< div class = "section" id = "id1299" >
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< h3 > < a class = "subsection-title" href = "#example" name = "example" > Example< / a > < / h3 >
< pre class = "literal-block" >
template< typename T > struct my
{
// ...
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< a href = "./assert-msg.html" class = "identifier" > BOOST_MPL_ASSERT_MSG< / a > (
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is_integral< T> ::value
, NON_INTEGRAL_TYPES_ARE_NOT_ALLOWED
, (T)
);
};
my< void*> test;
// In instantiation of `my< void*> ':
// instantiated from here
// conversion from `
// mpl_::failed************(my< void*> ::
// NON_INTEGRAL_TYPES_ARE_NOT_ALLOWED::************)(void*)
// ' to non-scalar type `mpl_::assert< false> ' requested
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< div class = "section" id = "id1300" >
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< h3 > < a class = "subsection-title" href = "#see-also" name = "see-also" > See also< / a > < / h3 >
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< p > < a class = "reference internal" href = "./asserts.html" > Asserts< / a > , < a class = "reference internal" href = "./assert.html" > BOOST_MPL_ASSERT< / a > , < a class = "reference internal" href = "./assert-not.html" > BOOST_MPL_ASSERT_NOT< / a > , < a class = "reference internal" href = "./assert-relation.html" > BOOST_MPL_ASSERT_RELATION< / a > < / p >
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<!-- Macros/Asserts//BOOST_MPL_ASSERT_NOT -->
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< td > < div class = "copyright-footer" > < div class = "copyright" > Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams< / div >
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