Jody Hagins <jody-boost-011304 <at> atdesk.com> writes:
Obviously, Kelvin does not want to make the ctor explicit, and even if he did, the change would most likely break existing code. However, some users may desire the pedantic behavior of an explicit constructor. What would be wrong with changing the ctor to be something like this...
template<typename ValueType> #if defined(BOOST_ANY_HAS_EXPLICIT_CTOR) explicit #endif any(const ValueType & value) : content(new holder<ValueType>(value)) { }
then users can get the functionality if they want it, but, by default, you get the same behavior. Since the implementation is an inline member template, there should be no linking issues.
I'd say (I could be wrong, though) that this would cause much trouble. You have two options for using your proposed solution: 1. Define BOOST_ANY_HAS_EXPLICIT_CTOR globally in your project, thus possibly breaking existing code (which might lie deep inside Boost itself.) 2. Define the macro locally, thus possibly violating ODR. In practise, chances are no problem arises since as you point out the ctor is an inliner, but ODR is not that permissive. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo