Cleaned up robot startup and cleanup/shutdown code (#77)

Cleaned up RobotBase, removed singleton list from SensorBase, and removed unused typedefs and NULL_TASK macro from HAL's Task.hpp. Making the robot class instance static fixed non-POD statics used by the instance during destruction from being destroyed first.

wpilibc/athena/src/DriverStation.cpp

@@ -58,8 +58,6 @@ DriverStation::DriverStation() {
   // It will signal when new packet data is available.
   HALSetNewDataSem(&m_packetDataAvailableCond);
 
-  AddToSingletonList();
-
   m_task = Task("DriverStation", &DriverStation::Run, this);
 }
 
@@ -104,8 +102,8 @@ void DriverStation::Run() {
  * @return Pointer to the DS instance
  */
 DriverStation& DriverStation::GetInstance() {
-  static DriverStation* instance = new DriverStation();
-  return *instance;
+  static DriverStation instance;
+  return instance;
 }
 
 /**

wpilibc/athena/src/RobotBase.cpp

@@ -17,20 +17,6 @@
 #include "Utility.h"
 #include "networktables/NetworkTable.h"
 
-RobotBase* RobotBase::m_instance = nullptr;
-
-void RobotBase::setInstance(RobotBase* robot) {
-  wpi_assert(m_instance == nullptr);
-  m_instance = robot;
-}
-
-RobotBase& RobotBase::getInstance() { return *m_instance; }
-
-void RobotBase::robotSetup(RobotBase* robot) {
-  std::printf("\n********** Robot program starting **********\n");
-  robot->StartCompetition();
-}
-
 /**
  * Constructor for a generic robot program.
  *
@@ -46,8 +32,6 @@ RobotBase::RobotBase() : m_ds(DriverStation::GetInstance()) {
   RobotState::SetImplementation(DriverStation::GetInstance());
   HLUsageReporting::SetImplementation(new HardwareHLReporting());
 
-  RobotBase::setInstance(this);
-
   NetworkTable::SetNetworkIdentity("Robot");
   NetworkTable::SetPersistentFilename("/home/lvuser/networktables.ini");
 
@@ -60,18 +44,6 @@ RobotBase::RobotBase() : m_ds(DriverStation::GetInstance()) {
   }
 }
 
-/**
- * Free the resources for a RobotBase class.
- * This includes deleting all classes that might have been allocated as
- * Singletons to they would never be deleted except here.
- */
-RobotBase::~RobotBase() {
-  SensorBase::DeleteSingletons();
-  delete m_task;
-  m_task = nullptr;
-  m_instance = nullptr;
-}
-
 /**
  * Determine if the Robot is currently enabled.
  * @return True if the Robot is currently enabled by the field controls.
@@ -111,17 +83,3 @@ bool RobotBase::IsTest() const { return m_ds.IsTest(); }
  * function was called?
  */
 bool RobotBase::IsNewDataAvailable() const { return m_ds.IsNewControlData(); }
-
-/**
- * This class exists for the sole purpose of getting its destructor called when
- * the module unloads.
- * Before the module is done unloading, we need to delete the RobotBase derived
- * singleton.  This should delete the other remaining singletons that were
- * registered.  This should also stop all tasks that are using the Task class.
- */
-class RobotDeleter {
- public:
-  RobotDeleter() {}
-  ~RobotDeleter() { delete &RobotBase::getInstance(); }
-};
-static RobotDeleter g_robotDeleter;

wpilibc/athena/src/SensorBase.cpp

@@ -19,7 +19,6 @@ const uint32_t SensorBase::kPwmChannels;
 const uint32_t SensorBase::kRelayChannels;
 const uint32_t SensorBase::kPDPChannels;
 const uint32_t SensorBase::kChassisSlots;
-SensorBase* SensorBase::m_singletonList = nullptr;
 
 static bool portsInitialized = false;
 void* SensorBase::m_digital_ports[kDigitalChannels];
@@ -57,37 +56,6 @@ SensorBase::SensorBase() {
   }
 }
 
-/**
- * Add sensor to the singleton list.
- *
- * Add this sensor to the list of singletons that need to be deleted when
- * the robot program exits. Each of the sensors on this list are singletons,
- * that is they aren't allocated directly with new, but instead are allocated
- * by the static GetInstance method. As a result, they are never deleted when
- * the program exits. Consequently these sensors may still be holding onto
- * resources and need to have their destructors called at the end of the
- * program.
- */
-void SensorBase::AddToSingletonList() {
-  m_nextSingleton = m_singletonList;
-  m_singletonList = this;
-}
-
-/**
- * Delete all the singleton classes on the list.
- *
- * All the classes that were allocated as singletons need to be deleted so
- * their resources can be freed.
- */
-void SensorBase::DeleteSingletons() {
-  for (SensorBase* next = m_singletonList; next != nullptr;) {
-    SensorBase* tmp = next;
-    next = next->m_nextSingleton;
-    delete tmp;
-  }
-  m_singletonList = nullptr;
-}
-
 /**
  * Check that the solenoid module number is valid.
  *