Basically, instead of having one button for config, one button
for graphics settings and so on, we now have just one settings
button which takes you to a screen where you pick between
config/graphics/GameCube controllers/Wii Remotes.
The main reason I want to do this is because people still have
trouble finding Overlay Controls in the "new" in-game menu.
Typically (depending on the screen size and the length of the
game name), the scrollable part of the menu can fit 4 items,
and merging Config and Graphics Settings into one item would
move Overlay Controls from 5th place to 4th place (assuming the
user doesn't have savestates enabled), which makes it findable
even for users who don't realize the menu can be scrolled.
The dialog that's shown when long pressing a game in the game
list is also shortened. While not a pressing matter, I think
it was getting a bit long.
An additional reason to do this is because we probably will
want to make it possible to edit the controller settings
from the in-game menu at some point in the future. With the
old approach, this would require us to dedicate a whopping 4
menu items just for settings (not including Overlay Controls),
which I think is excessive.
Introduces the system class that will eventually contain all relevant
system state, as opposed to everything being distributed all over the
place as global variables.
Throughout the codebase we have code that from its interface-view, does
not actually require its dependencies to be described in the interface,
and we routinely run into issues with initialization where we sometimes
make use of a facility before it's been initialized, which leads to
annoying to debug cases, because the reader needs to run through the
codebase and see what order things get initialized in, and how they're
being used. This is particularly a frequent issue in the video code.
Further, we also have a lot of code that makes use of file-scope
variables (many of which are non-trivial), which must all be default
initialized before the application can actually enter main(). While this
may not be a huge issue in itself, some of these are allocating, which
means that the application may need to use memory that it otherwise
wouldn't need to (e.g. when a game isn't running, this excess memory is
being used).
Being able to wrap all these subsystems into objects would be nicer,
since they can be constructed when they're actually needed. Them being
objects also means we can better express dependencies on subsystems as
types directly in the interface, making them explicit to the reader
instead of a change randomly blowing up, said reader inspecting it, and finding
out that something needed to be initialized beforehand. With the global
turned into a function parameter, the dependency is explicit and they
know just by reading it, that the given subsystem needs to be in a valid
state before calling the function.
For a prior example of an emulator that has moved to this model, see
yuzu, which has been migrated off of global variables all over the place
and replaced with a system instance (which has now reached the stage,
where the singleton can be removed).
LC