MAMEWorld Forums - EmuChat - Dev question: is ioport

Hello, this is a question for MAME developers.

Some background: I have an code base that I wrote and have been maintaining for maybe a year and a half now. I call it libmame. It wraps the MAME source code with a stable, well-documented, featureful API that allows any program to run games via the MAME "engine". I use it in a frontend program that I have been developing off and on for a while now with some unique features, which I won't go into detail on right now.

One thing that has been kind of a pain for a while now is the changes to the MAME code subsystems that have been happening - basically, the C++-ification of parts of MAME. I say this is a pain, what I really mean is that it's been a pain for me; I am sure that overall it is a good thing for MAME and that there are benefactors for the changes (MAME driver developers). I mention that it is has been a pain for me mostly to try to evoke sympathy so that MAME devs take enough pity on me to answer my question here and any other questions I end up asking on this topic. With every major MAME release, for the past year or so there have been re-jiggerings of many MAME internals that require me to update my libmame code, and it's not always been obvious how to do this. So far I've done OK though, I always figure it out; but it is a pain (once again, not trying to complain).

Right now the major overhaul of the input API is giving me fits. I only ever understood just enough of the old API to utilize it for my purposes; I never felt like I had a great grasp of its overall architecture or use. Now it's been converted mostly to C++ classes and I am more lost than ever. I feel like in order to adapt libmame to use the new API, I really should understand the input architecture better. So here is my first question in that regards.

There is a class called input_type_entry; two of its constructor parameters are "group" and "player", of types ioport_group and int respectively. The player parameter is described (via the code docs of the member variable it is used for) as "player number (0 is player 1)". But ioport_group is an enumeration which already includes IPG_PLAYER1, IPG_PLAYER2, ..., IPG_PLAYER8. This seems redundant.

Am I misunderstanding something, or is either the player member variable of input_type_entry, or the IPG_PLAYER{1,...,8} enumeration values of ioport_group redundant?