Re: [Boost-users] Need boost's help with poor design

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 what exactly is that doing?

template 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 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