# GetClassName

VTKExamples/Cxx/Utilities/GetClassName

### Description

This example demonstrates the GetClassName function. This should be available for every VTK class. This is extremely helpful for debugging - you are able to determine the type of a variable that is passed as an abstract type. With this information, the list of functions that can be called on this variable can be determined.

The example illustrates alternative ways to get the "name" of a class. Notice that the GetClassName provides a simple and useful solution.

### Code

GetClassName.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPoints.h>
    #include <typeinfo>

    static const char *unmangleName (const char * name);

    int main(int, char *[])
    {
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();

      std::cout << "points->GetClassName():             "
                << points->GetClassName() << std::endl;
      std::cout << "Mangled" << std::endl;
      std::cout << "\ttypeid(points).name():              "
                << typeid(points).name() << std::endl;
      std::cout << "\ttypeid(points.GetPointer()).name(): "
                << typeid(points.GetPointer()).name() << std::endl;
      std::cout << "Unmangled" << std::endl;
      std::cout << "\ttypeid(points.GetPointer()).name(): "
                << unmangleName(typeid(points).name()) << std::endl;
      std::cout << "\ttypeid(points.GetPointer()).name(): "
                << unmangleName(typeid(points.GetPointer()).name()) << std::endl;
      return EXIT_SUCCESS;
    }

    // Better name demangling for gcc
    #if __GNUC__ > 3 || ( __GNUC__ == 3 && __GNUC_MINOR__ > 0 )
    #define GCC_USEDEMANGLE
    #endif

    #ifdef GCC_USEDEMANGLE
    #include <cstdlib>
    #include <cxxabi.h>
    #endif

    const char *unmangleName (const char * name)
    {
    #ifdef GCC_USEDEMANGLE
      char const *mangledName = name;
      int         status;
      char *      unmangled = abi::__cxa_demangle(mangledName, 0, 0, &status);
      return unmangled;
    #else
      return name;
    #endif
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(GetClassName)

    find_package(VTK COMPONENTS
      vtkCommonCore QUIET)
    if (NOT VTK_FOUND)
      message("Skipping GetClassName: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(GetClassName MACOSX_BUNDLE GetClassName.cxx )
      target_link_libraries(GetClassName PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(GetClassName MACOSX_BUNDLE GetClassName.cxx )
      target_link_libraries(GetClassName PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS GetClassName
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build GetClassName

Click here to download GetClassName and its CMakeLists.txt file. Once the tarball GetClassName.tar has been downloaded and extracted,

    cd GetClassName/build

If VTK is installed:

    cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

    cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

    make

and run it:

    ./GetClassName

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.