Linear OpModes have several major downsides with no obvious solutions:
- Some things stop working automatically--e.g. in a linear opmode,
simulation will not work out-of-the-box; the user must explicitly call
sim themselves. there's a few other things we do periodically, but this
is the big one (it also forces some decisions on other parts of the
library—eg if we want Tunable to work in linear without the user
manually calling refresh, we have to run it on a background thread,
which means it must be thread safe throughout). We can help in some
areas (e.g. have sleep functions call background things), but if the
user is writing a loop that waits to drive a certain distance with no
sleep, it's an easy footgun
- Writing code with no sleeps is easy to do, and can hog an entire
processing core easily--yes, there's more than one core, but it could
still easily impact e.g. vision processing
- Many people I've talked to want robot-level periodic and periodic sim
functions. Given linear opmodes, we have two options, neither of which
is great: (1) don't provide robot-level periodic functions, and the
users who want those must set those up themselves and remember to call
them explicitly from every periodic opmode, or (2) provide them, but
only call them automatically from periodic opmodes, which could be
confusing for linear opmode users (they'd have to call them manually if
they wanted them). Currently we do (1) but someone in the community
already opened a change to do (2).
- Restarting the robot program fixes the "stuck in auto for the rest of
the match" problem but still feels like an ugly hack because the startup
time is not unlikely to make the robot not immediately ready for teleop
Removing LinearOpMode resolves these issues by moving to a periodic-only
structure. We can address the few notable use cases of LinearOpMode
(e.g. very basic autonomous sequences) in other ways such as Blocks
generated code, better state machine tutorials/documentation, etc.
User code:
- OpModeRobot used as the robot base class
- LinearOpMode and PeriodicOpMode are provided opmode base classes
- In Java, annotations can be used to automatically register opmode classes
Additional user code functionality:
- OpMode (string) is available in addition to the overall
auto/teleop/test robot mode
- OpMode does not indicate enable (enable/disable is still separate)
- The HAL API uses integer UIDs; these are exposed at the user API level
as well for faster checks
- User code creates opmodes on startup (these have name, category,
description, etc).
DS:
- DS will present opmode selection lists for auto and teleop for
match/practice. During a match, the DS will automatically activate the
selected opmode in the corresponding match period.
- For testing, an overall mode is selected (e.g. teleop/auto/test) and a
single opmode is selected
Future work:
- Command framework support/integration
- Python annotation support
- Unit tests (needs race-free DS sim updates)
- Porting of examples
Co-authored-by: Joseph Eng <91924258+KangarooKoala@users.noreply.github.com>
