[wpilib] Add a few unit overloads

[Murat65536]

Closes #8191

[calcmogul]

fyi, these changes can be ported to C++ as well, despite the issue specifically mentioning Java.

[Murat65536]

fyi, these changes can be ported to C++ as well, despite the issue specifically mentioning Java.

@calcmogul
I have very little experience with C++ compared to Java and VS Code shows a bunch of errors in any C++ file I try to open. Might be because I'm on Linux.

I see this:

allwpilib/wpilibc/src/main/native/cpp/TimedRobot.cpp

Lines 106 to 107 in ee3d55e

	void TimedRobot::AddPeriodic(std::function<void()> callback,
	units::second_t period, units::second_t offset) {

What I don't see is where second_t is defined. I also don't see what units is. Something external? I installed Windows. I see it now. Annoying that eveything's broken on Linux but I guess it makes sense. C++ isn't cross-platform until you make it behave that way.

[ThadHouse]

What I don't see is where second_t is defined. I also don't see what units is. Something external? I installed Windows. I see it now. Annoying that eveything's broken on Linux but I guess it makes sense. C++ isn't cross-platform until you make it behave that way.

Linux definitely does work. However by default in allwpilib, the project intellisense generation doesn't run. You can run ./gradlew generateVsCodeConfig to force that generation.

[Murat65536]

That makes more sense. There's probably a reason that it doesn't when I open up the project that I don't know. Maybe bad stuff happens if I close the project before the command completes?

[Murat65536]

@calcmogul
Should I be using templates for this? Sorry if I'm missing something really easy or obvious. I don't have much experience with C++, especially in large projects.

[KangarooKoala]

You can just use the SI units (units::second_t, units::hertz_t, units::meter_t, etc.) for the C++ version, since our C++ units library will automatically convert between compatible unit types. (For example, you could pass 1_ft as an argument to a method expecting units::meter_t)

[Murat65536]

On the C++ tests, I'm getting this message:
more than one instance of overloaded function "insert frequency overloaded function" matches the argument list
From my understanding, both units::second_t and units::hertz_t are perfectly fine with accepting plain numbers. They don't need to be a specific type like in Java. I don't have experience with all the quirks of C++ but based on this, it doesn't seem possible to overload functions with frequency. Maybe I'm wrong?
The workflows also seem to support this:

wpilibc/src/test/native/cpp/TimerTest.cpp(87): error C2668: 'frc::Timer::HasElapsed': ambiguous call to overloaded function
    SET RUNFILES_MANIFEST_ONLY=1
C:\bazelroot\vbgseepj\execroot\__main__\bazel-out\arm64_windows-fastbuild\bin\wpilibc\_virtual_includes\wpilibc.static\frc/Timer.h(105): note: could be 'bool frc::Timer::HasElapsed(units::frequency::hertz_t) const'
    SET TEMP=C:\Users\RUNNER~1\AppData\Local\Temp
C:\bazelroot\vbgseepj\execroot\__main__\bazel-out\arm64_windows-fastbuild\bin\wpilibc\_virtual_includes\wpilibc.static\frc/Timer.h(103): note: or       'bool frc::Timer::HasElapsed(units::time::second_t) const'
    SET TMP=C:\Users\RUNNER~1\AppData\Local\Temp
wpilibc/src/test/native/cpp/TimerTest.cpp(87): note: while trying to match the argument list '(units::time::millisecond_t)'
    SET VSLANG=1033

[KangarooKoala]

First: Please make the following changes to the C++ overload set to match Java.

• Add void StartPeriodic(units::hertz_t frequency); to Notifier.h. (Don't forget to copy-paste the doc comment above void StartPeriodic(units::second_t period); and to replace period with frequency.) The implementation can be StartPeriodic(1.0 / frequency);.
• Add explicit TimedRobot(units::hertz_t frequency = 1 / kDefaultPeriod);. (Again, copy-paste the doc comment from the units::second_t version and replace period with frequency.) For this one, you'll want to use the following syntax in the TimedRobot.cpp file to delegate to the main constructor:

  TimedRobot::TimedRobot(units::hertz_t frequency) : TimedRobot{1 / frequency} {}

• Remove Timer::HasElapsed(units::hertz_t)- The Java equivalent would be Timer.hasElapsed(Frequency), but that is intentionally not present, since it's not useful.
• Remove Watchdog::SetTimeout(units::hertz_t)- Similar to the above note for Timer::HasElapsed().
• Remove BooleanEvent::Debounce(units::hertz_t, frc::Debouncer::DebounceType)- Similar to the above note for Timer::HasElapsed().

Second: The compilation error seems to be a problem with the C++ units library we're currently using. I'll work on a fix.

[KangarooKoala]

Nice work!

[KangarooKoala]

Seems okay to me for what it's worth, though you should probably run wpiformat -f wpilibc/src/main/native/cpp/TimedRobot.cpp to make sure the long constructor line doesn't need to be broken up. (If you haven't installed wpiformat, just run python3 -m pip install wpiformat)

[calcmogul]

This PR is blocked on #8267.

[KangarooKoala]

Seems good to me, for what it's worth.