From boost-users  Mon Jul 10 09:19:54 2006
From: Marc Mutz <marc () klaralvdalens-datakonsult ! se>
Date: Mon, 10 Jul 2006 09:19:54 +0000
To: boost-users
Subject: [Boost-users] [variant] apply_visitor to rvalue variant
Message-Id: <200607101119.55677.marc () klaralvdalens-datakonsult ! se>
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Hi,

My gcc 4.0 doesn't let me call apply_visitor on an rvalue variant. This is =
due=20
to the Variant argument being a non-const reference, I guess. Is this a=20
deliberate design decision (if so, the rationale should be documented), an=
=20
oversight (in that case, it should be fixed), or a compiler bug (highly=20
unlikely, since all of gcc 3.2 through 4.1 would then have it).

Testcase (=3D=3D usecase) attached.

Thanks,
Marc

=2D-=20
Marc Mutz -- marc@klaralvdalens-datakonsult.se, mutz@kde.org
Klar=E4lvdalens Datakonsult AB, Platform-independent software solutions

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#include <boost/variant.hpp>
#include <boost/lexical_cast.hpp>

#include <string>

typedef boost::variant<int, double, std::string> Variant;

Variant foo();

struct ToString : boost::static_visitor<std::string> {
    template <typename T>
    std::string operator()( const T & t ) const {
        return boost::lexical_cast<std::string>( t );
    }
};

int main() {
    const std::string str = apply_visitor( ToString(), foo() );
}

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