Ferdinand Prantl wrote:
Thanks for your suggestions! Niels, you nailed it! [...] The current requirements of boost::any ensure that the contained object is always valid there (if not used too wildly). I should have thought about the copying myself... :-) Your wrapper is an elegant solution isolating the construction differences from the rest of the holder template.
I'm glad you like it. :-) But how do you use it in practice? The added boost::any array support I suggested would require you to always specify the number of character, when retrieving C-style string (char[N]) from a boost::any. Wouldn't it? Maybe an extra function, boost::any::size_of_value(), would be helpful, returning the number of bytes of the stored object. What do you think? How would you deal with various string lengths, within your application? BTW, after re-reading, I found two shortcomings to the implementation as I originally suggested, caused by the implementation of the wrapper: explicit wrapper(const ElementType (& value)[NumberOfElements]) { std::copy(value, value + NumberOfElements, data); } First of all, it doesn't support storing a multidimentional array (e.g. int[42][69]) into a boost::any. Secondly, it copies its argument by means of copy-assignment, instead of copy-initialization. So when T is a class, wrapping an array of T would do default-construction + assignment, instead of just copy-construction. I'm pretty sure that both of these issues can be solved, though. The data would need to be stored in a boost::aligned_storage, and the copying should probably be done by placement-new, to solve the second issue. Anyway, these two issues are irrelevant to your request for C-style string support... Good luck, Niels