问题
Is it possible to store states in C++ metaprograms? I'm not entirely sure what I mean, but I want a template class that can be "assigned" to, e.g. state::value can be changed via the use of C++ templates.
I know I probably sound very vague, but I hope someone understands what I'm talking about (also please no Boost.MPL).
回答1:
It's not possible, the TMP part of C++ is a purely functional language without the concept of side effects.
回答2:
That would be a heaven for bugs.
It would also violate the template single-instantiation rule, and it will blow up the size of your program (not to mention confusing the heck out of you).
来源：https://stackoverflow.com/questions/6105994/storing-states-in-c-metaprogramming