CTTI

Compile Time Type Information for the C++ programming language.

Background

We know C++ is a statically typed compiled language, but it's disappointing that we cannot even get the name of a C++ type at compile time, having to use RTTI (Run Time Type Information) which introduces a lot of overhead. In fact, that's one of the most feared features of C++, usually disabled in performance dependent scenarios such as videogames programming.

This library aims to provide features similar to RTTI std::type_info at compile-time, currently constexpr type name and a constexpr replacement of std::type_index for indexing maps with types.

#include "ctti/type_id.hpp"

int main()
{
    static_assert(ctti::type_id<int>() != ctti::type_id("hello"), "compile-time type-id comparison");
    
    std::unordered_map<ctti::type_id_t, std::size_t> sizeof_map;
    
    sizeof_map[ctti::type_id<int>()] = sizeof(int);
}

Support and current status

This was tested on both GCC 5.2.0 and Clang 3.6.2. It's fairly unstable (I'm currently working on it), and it leads to ugly ICEs whenever the constexpr machinery fails.

Current state: Bugs...

ctti::type_id comparison and hashing works correctly, but I'm trying to find a bug that causes type_ide::name() to return empty or even corrupted strings. I'm sure there's something wrong with the ctti::detail::string::substr() function. I'm on it :)

Acknowledgments

Thanks a lot to Jonathan "foonathan" Müller, both for the constexpr hash and the idea for the __PRETTY_FUNCTION__ trick.

License

This project is licensed under the MIT license. See LICENSE.md for more details.

FlorianChevassu / ctti