AMDG Robert Dailey wrote:
The term 'inherit' here does not refer to class inheritance obviously. It's an unusual usage of the term to me. When you do inherit<empty_base, WalkPacket> what exactly is that doing?
template<class T1, class T2> struct inherit : T1, T2 {};
Is it joining them in a list container or something? What is the resulting type of mpl::inherit_linearly::type? Is the result of mpl::inherit_linearly::type implicitly constructible from an mpl::transform::type?
The result of the inherit_linearly call inherits using multiple inheritence from all the types in the sequence.
I'm going to read over the docs a few more times in the meantime to see if I can grasp this concept. Also, I'm not seeing how you're filling in the 2 placeholders in the signal_holder typedef.
mpl::inherit_linearly treats the second argument as a binary lambda expression. It is very similar to the runtime std::accumulate. Think of inherit<_, _> as the MPL equivalent of a function object that returns inherit<T1, T2> for arguments T1 and T2.
Also, mpl::vector has a max size limit I'm sure. Right now we have a very minimal set of packet types, but in the future we have to consider the possibility that 100+ packet types will exist (the final number is ultimately unknown). If this is true, I doubt mpl::vector would be usable anymore since 100 seems too large for it. This makes me feel like I'm going to have to resort to a completely template-less approach. I might have to send a generic Packet object to all subscribers, which has a ::Get() method that performs a static_cast<>() to the concrete type based on an ID.
MPL allows configuration to make vector able to hold larger numbers of types. If you need such a large number of Packets, compilation may be very slow with metaprogramming. In Christ, Steven Watanabe