Re: [Boost-users] Is there an elegant way to initialize aninstanceof boost::any with a C-style string constant?

Ferdinand Prantl wrote:

I use boost::any for serialization and deserialization of both user-provided values and hard-coded constants. Stream output has to be done a little clumsily by a custom operator<<() which consists of a big if/elseif code block deciding what to do according to boost::any::type().

Would it be helpful to you if boost::any would have a function to retrieve its value "as a string"? I /think/ such a function, any::str(), could be implemented quite easily, as a pure virtual function of any::placeholder, implemented within any::holder<ValueType> as follows: virtual const std::string str() const { using any_implementation_details::operator<<; std::ostringstream stream; stream << held; return stream.str(); } The namespace any_implementation_details would have an empty default implementation of operator<<: namespace any_implementation_details { template void operator<<(std::basic_ostream&, const ValueType &) { // Only called when ValueType doesn't have a better operator<<. } } But if ValueType would have its own operator<<, the compiler would pick that one instead. boost::any::str() would just forward the result from placeholder::str(): std::string str() const { return content ? content->str() : std::string(); } I think it would work for any type of value, including char-pointers and std::strings. In the future it could even be used for char-arrays, when array support is added. :-) What do you think? Would it simplify your serialization?

Thank you very much for your deep insight!

You're welcome :-) Kind regards, Niels PS, For those who missed it, there's another thread on this iussue at the Boost developers' mailing list, "[boost] An elegant way to initialize an instance of boost::anywith a C-style string constant", http://thread.gmane.org/gmane.comp.lib.boost.devel/177324