[boost] Using shared_ptr needlessly results in ambiguous function call

28 Aug 2006

      Hi,

I posted about this a week or so ago, but didn't get any response.  So
I'm trying again.

Is there any reason we wouldn't want to add this constructor to
shared_ptr so that it can work more like a real pointer and not result
in ambiguous function call error with overloaded functions?

template<class Y>
shared_ptr(shared_ptr<Y> const & r, typename enable_if<
    typename is_convertible<Y*, T*>::type, void*>::type = 0): px(r.px), pn(r.pn)
{
}

Thanks,
Phillip Hellewell

P.S.  This is an example of code that will result in an ambiguous
call, taken directly from
http://lists.boost.org/Archives/boost/2005/12/97817.php

class A{};
class B{};
class C : public A{};

void foo( boost::shared_ptr<A> pa ){
    std::cout << "A";
}

void foo( boost::shared_ptr<B> pb ){
    std::cout << "B";
}

int main(){
    boost::shared_ptr<C> ptr(new C);
    foo( ptr );
    return 0;
}