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< title > The MPL Reference Manual: apply_wrap< / title >
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< table class = "header" > < tr class = "header" > < td class = "header-group navigation-bar" > < span class = "navigation-group" > < a href = "./apply.html" class = "navigation-link" > Prev< / a > < a href = "./unpack-args.html" class = "navigation-link" > Next< / a > < / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./apply.html" class = "navigation-link" > Back< / a > < a href = "./unpack-args.html" class = "navigation-link" > Along< / a > < / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./invocation.html" class = "navigation-link" > Up< / a > < a href = "../refmanual.html" class = "navigation-link" > Home< / a > < / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./refmanual_toc.html" class = "navigation-link" > Full TOC< / a > < / span > < / td >
< td class = "header-group page-location" > < a href = "../refmanual.html" class = "navigation-link" > Front Page< / a > / < a href = "./metafunctions.html" class = "navigation-link" > Metafunctions< / a > / < a href = "./invocation.html" class = "navigation-link" > Invocation< / a > / < a href = "./apply-wrap.html" class = "navigation-link" > apply_wrap< / a > < / td >
< / tr > < / table > < div class = "header-separator" > < / div >
< div class = "section" id = "apply-wrap" >
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< h1 > < a class = "toc-backref" href = "./invocation.html#id1526" > apply_wrap< / a > < / h1 >
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< div class = "section" id = "id894" >
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< h3 > < a class = "subsection-title" href = "#synopsis" name = "synopsis" > Synopsis< / a > < / h3 >
< pre class = "literal-block" >
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template<
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typename F
>
struct apply_wrap0
{
typedef < em > unspecified< / em > type;
};
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template<
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typename F, typename A1
>
struct apply_wrap1
{
typedef < em > unspecified< / em > type;
};
< em > ...< / em >
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template<
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typename F, typename A1,< em > ...< / em > typename An
>
struct < a href = "./apply-wrap.html" class = "identifier" > apply_wrap< / a > < em > n< / em >
{
typedef < em > unspecified< / em > type;
};
< / pre >
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< h3 > < a class = "subsection-title" href = "#description" name = "description" > Description< / a > < / h3 >
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< p > Invokes a < a class = "reference internal" href = "./metafunction-class.html" > Metafunction Class< / a > < tt class = "literal" > < span class = "pre" > F< / span > < / tt > with arguments < tt class = "literal" > < span class = "pre" > A1< / span > < / tt > ,... < tt class = "literal" > < span class = "pre" > An< / span > < / tt > .< / p >
< p > In essence, < tt class = "literal" > < span class = "pre" > < a href = "./apply-wrap.html" class = "identifier" > apply_wrap< / a > < / span > < / tt > forms are nothing more than syntactic wrappers around
< tt class = "literal" > < span class = "pre" > F::< a href = "./apply.html" class = "identifier" > apply< / a > < A1,...< / span > < span class = "pre" > An> ::type< / span > < / tt > / < tt class = "literal" > < span class = "pre" > F::< a href = "./apply.html" class = "identifier" > apply< / a > ::type< / span > < / tt > expressions (hence the name).
They provide a more concise notation and higher portability than their
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underlaying constructs at the cost of an extra template instantiation.< / p >
< / div >
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< div class = "section" id = "id896" >
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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/apply_wrap.hpp" class = "header" > boost/mpl/apply_wrap.hpp< / a > >
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< div class = "section" id = "id897" >
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< h3 > < a class = "subsection-title" href = "#parameters" name = "parameters" > Parameters< / a > < / h3 >
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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" > F< / span > < / tt > < / td >
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< td > < a class = "reference internal" href = "./metafunction-class.html" > Metafunction Class< / a > < / td >
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< td > A metafunction class to invoke.< / td >
< / tr >
< tr > < td > < tt class = "literal" > < span class = "pre" > A1< / span > < / tt > ,... < tt class = "literal" > < span class = "pre" > An< / span > < / tt > < / td >
< td > Any type< / td >
< td > Invocation arguments.< / td >
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< / tbody >
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< / div >
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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 < a class = "reference internal" href = "./metafunction-class.html" > Metafunction Class< / a > < tt class = "literal" > < span class = "pre" > f< / span > < / tt > and arbitrary types < tt class = "literal" > < span class = "pre" > a1< / span > < / tt > ,... < tt class = "literal" > < span class = "pre" > an< / span > < / tt > :< / p >
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< pre class = "literal-block" >
typedef < a href = "./apply-wrap.html" class = "identifier" > apply_wrap< / a > < em > n< / em > < f,a1,< em > ...< / em > an> ::type t;
< / 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" > Any type.< / td >
< / tr >
< tr class = "field" > < th class = "field-name" > Semantics:< / th > < td class = "field-body" > If < tt class = "literal" > < span class = "pre" > n< / span > < span class = "pre" > > < / span > < span class = "pre" > 0< / span > < / tt > , equivalent to < tt class = "literal" > < span class = "pre" > typedef< / span > < span class = "pre" > f::< a href = "./apply.html" class = "identifier" > apply< / a > < a1,...< / span > < span class = "pre" > an> ::type< / span > < span class = "pre" > t;< / span > < / tt > ,
otherwise equivalent to either < tt class = "literal" > < span class = "pre" > typedef< / span > < span class = "pre" > f::< a href = "./apply.html" class = "identifier" > apply< / a > ::type< / span > < span class = "pre" > t;< / span > < / tt > or
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< tt class = "literal" > < span class = "pre" > typedef< / span > < span class = "pre" > f::< a href = "./apply.html" class = "identifier" > apply< / a > < > ::type< / span > < span class = "pre" > t;< / span > < / tt > depending on whether < tt class = "literal" > < span class = "pre" > f::< a href = "./apply.html" class = "identifier" > apply< / a > < / span > < / tt > is
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a class or a class template.< / td >
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< h3 > < a class = "subsection-title" href = "#example" name = "example" > Example< / a > < / h3 >
< pre class = "literal-block" >
struct f0
{
template< typename T = int > struct < a href = "./apply.html" class = "identifier" > apply< / a >
{
typedef char type;
};
};
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struct g0
{
struct < a href = "./apply.html" class = "identifier" > apply< / a > { typedef char type; };
};
struct f2
{
template< typename T1, typename T2 > struct < a href = "./apply.html" class = "identifier" > apply< / a >
{
typedef T2 type;
};
};
typedef < a href = "./apply-wrap.html" class = "identifier" > apply_wrap< / a > < tt class = "literal" > < span class = "pre" > 0< / span > < / tt > < f0 > ::type r1;
typedef < a href = "./apply-wrap.html" class = "identifier" > apply_wrap< / a > < tt class = "literal" > < span class = "pre" > 0< / span > < / tt > < g0 > ::type r2;
typedef < a href = "./apply-wrap.html" class = "identifier" > apply_wrap< / a > < tt class = "literal" > < span class = "pre" > 2< / span > < / tt > < f2,int,char > ::type r3;
< a href = "./assert.html" class = "identifier" > BOOST_MPL_ASSERT< / a > (( is_same< r1,char> ));
< a href = "./assert.html" class = "identifier" > BOOST_MPL_ASSERT< / a > (( is_same< r2,char> ));
< a href = "./assert.html" class = "identifier" > BOOST_MPL_ASSERT< / a > (( is_same< r3,char> ));
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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 = "./metafunctions.html" > Metafunctions< / a > , < a class = "reference internal" href = "./invocation.html" > invocation< / a > , < a class = "reference internal" href = "./apply.html" > apply< / a > , < a class = "reference internal" href = "./lambda.html" > lambda< / a > , < a class = "reference internal" href = "./quote.html" > quote< / a > , < a class = "reference internal" href = "./bind.html" > bind< / a > , < a class = "reference internal" href = "./protect.html" > protect< / a > < / p >
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<!-- Metafunctions/Invocation//unpack_args |30 -->
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< table class = "footer" > < tr class = "footer" > < td class = "header-group navigation-bar" > < span class = "navigation-group" > < a href = "./apply.html" class = "navigation-link" > Prev< / a > < a href = "./unpack-args.html" class = "navigation-link" > Next< / a > < / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./apply.html" class = "navigation-link" > Back< / a > < a href = "./unpack-args.html" class = "navigation-link" > Along< / a > < / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./invocation.html" class = "navigation-link" > Up< / a > < a href = "../refmanual.html" class = "navigation-link" > Home< / a > < / span > < span class = "navigation-group-separator" > | < / span > < span class = "navigation-group" > < a href = "./refmanual_toc.html" class = "navigation-link" > Full TOC< / a > < / span > < / td >
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< td > < div class = "copyright-footer" > < div class = "copyright" > Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams< / div >
Distributed under the Boost Software License, Version 1.0. (See accompanying
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