template<typename... Ts>

psl::ecs::on_combine struct

specialized tag of on_add

Will filter components based on when the given combination first appears. This provides a way to not care if component X, or component Y was added last and instead only cares if they both are used in a combination for the first time. This is ideal for systems that need to do something based on the creation of certain components. Take core::ecs::components::renderable and core::ecs::components::transform as example, who, when combined, create a draw call. The system that creates them should not need to care if the transform was added first or last.