On 12 Jan 2012, at 13:30, Mark Snelling wrote:

I'm having a problem with Boost.Tuple virtual functions. Consider the code below, I would have expected the output to be "B::foo()" but instead get "A::foo()". Am I missing something here?

Yes, if you copy a A&, you end up with an A. This is known as 'slicing', and can be a pain. It has nothing to do with boost, or tuple. Chris

#include <boost/tuple/tuple.hpp> #include <iostream>

class A { public: virtual void foo() { std::cout << "A::foo()" << std::endl; } };

class B :public A { public: void foo() { std::cout << "B::foo()" << std::endl; } };

boost::tuple< A > make( const A& a ) { return boost::make_tuple( a ); }

int main( int argc, char* argv[] ) { B b; make( b ).get< 0 >().foo();

return 0; }

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