Crunch

Tuples and Templates In C++, tuples are a collection of values of heterogenous types. You can access different elements at compile time via the get method, while the std::tuple_size and std::tuple_element APIs provide metadata about the collection’s structure. Classes that satisfy this “Tuple Protocol” in the STL - and can therefore utilize the techniques in this article - include std::tuple, std::pair, std::array, and some types in the std::ranges library. When we use templates, the C++ Core Guidelines tell us to specify concepts for all parameters. This article demonstrates a few methods for applying concepts to tuples and their individual elements. While developing Crunch, I had quite a few use cases for applying template concepts to tuples and found some good - and not so good - ways to do it. I did not find any clear explanations of the syntax proposed for those solutions, or how you could arrive at them yourself. I hope that by the end of this article, you feel comfortable writing template concepts targeting std::tuple parameters in your own projects! ...

There are a lot of different tools for defining structured messages and working with their serialized representations for communication over-the-wire. I have worked with open source, closed source, and hand-rolled toolchains tackling this problem. Every tool I have seen has a serious design flaw that makes them very difficult to use correctly in mission-critical contexts. Validation - both of individual fields and of whole messages - is completely decoupled from the message definitions. This is a fundamental gap in how messages are specified. A comprehensive description of what makes a message valid is equally important in system design as the types and names of the fields. ...