Porting code from MRPT 1.{3,4,5} to MRPT 2.*

MRPT 2.0 includes several fundamental changes, most of them related to API clean ups and the introduction of C++14 as the minimum supported version of the language.

Existing user applications may need to be adapted to continue compiling and working as usual after updating to MRPT 2.*:

Mandatory changes

• Your project must use C++14. Using CMake this is easy by adding this right after your top-level PROJECT:

  CMAKE_MINIMUM_REQUIRED(VERSION 3.1)
  set (CMAKE_CXX_STANDARD 14)  # Require C++14

• Smart pointers are now standard std::shared_ptr<> instead of those based on stlplus. Required changes:
  • ptr.clear() –> ptr.reset(). Also, notice that the former stlplus semantics of clear() deleting all copies of the object, as hold by different smart pointers, is no longer maintained. There is no longer such a possibility, since the C++11 standard does not allow it to happen (and it makes sense in this way).
  • ptr.clear_unique() –> ptr.reset(). (Read this note above)
  • ptr.make_unique() does no longer exists, and does not make sense (read above).
  • ptr.pointer() –> ptr.get()
• Smart pointers have been renamed from CFooPtr to the more standard CFoo::Ptr, with a new pointer-to-const version CFoo::ConstPtr.
  • Note: To help with porting and maintaining existing code bases, MRPT >=1.5.4 offers MRPT2-like CFoo::Ptr smart pointers. Refer to changelog of mrpt 1.5.4.
• You can keep using code like:

  CFoo::Ptr o = CFoo::Create();

  in MRPT 2.0 to create a smart pointer, but can also use std::make_shared<CFoo>(), or mrpt::make_aligned_shared<CFoo>() if the class must be memory-aligned (typically, if it contains Eigen matrices). The arguments of Create() are now perfectly-forwarded to the class ctor, so the parameter list must exactly match any of the available ctors.
• Smart pointer typecasting now is done via C++11 standard functions:
  • Example: Old code

    CObservationPtr obs = getObsFromSomewhere();
    CObservationGPSPtr gps = CObservationGPS(obs);

    becomes pure C++14 in MRPT 2.0:

    CObservation::Ptr obs = getObsFromSomewhere();
    CObservationGPS::Ptr gps = std::dynamic_pointer_cast<CObservationGPS>(obs);

    or, if you need to keep your code compatible with MRPT >=1.5.4:

    CObservation::Ptr obs = getObsFromSomewhere();
    CObservationGPS::Ptr gps = mrpt::ptr_cast<CObservationGPS>::from(obs);

• Threads, semaphores and mutexes are now based on C++11 standard library. Required changes:
  • mrpt::synch::CCriticalSection cs; –> std::mutex cs;
  • mrpt::synch::CCriticalSectionLocker lock(&cs); –> std::lock_guard<std::mutex> lock(cs);
  • mrpt::system::TThreadHandle h = mrpt::system::createThread(...); –> std::thread h = std::thread(...);
  • mrpt::system::sleep(5); –> std::this_thread::sleep_for(5ms);
  • mrpt::synch::CSemaphore sem; sem.waitForSignal(timeout); sem.release(); –> std::promise<void> sem; auto fut = sem.get_future(); fut.wait_for(...); sem.set_value();
• mrpt::utils::CObject::duplicate() has been removed, use the equivalent (redundant) mrpt::utils::CObject::clone().
• CSerialPort, mrpt::utils::net, sockets: have been moved to its own new module [mrpt-comms] under namespace mrpt::comms.
• Static variables have been dropped in favor of global getter/setter functions. This allowed removing all DLL import/export macros for Windows compilers. Important changes are:
  • mrpt::math::randomGenerator –> mrpt::math::getRandomGenerator()
  • mrpt::global_settings old static variables have been replaced by getter/setter functions.

Optional changes

• Use the Foo::ConstPtr smart pointers when possible instead of its non-const counterpart.