C++ API

class_loader

The class_loader package is a ROS-independent package for loading plugins during runtime and the foundation of the higher level ROS pluginlib library. class_loader utilizes the host operating system’s runtime loader to open runtime libraries (e.g. .so/.dll/dylib files), introspect the library for exported plugin classes, and allows users to instantiate objects of said exported classes without the explicit declaration (i.e. header file) for those classes.

class_loader VS pluginlib

class_loader is used in the implementation of the higher-level ROS package pluginlib which is the encouraged method for loading plugins in the ROS ecosystem. You should use class_loader when creating plugins intended for non-ROS packages and pluginlib when exporting plugins to ROS packages.

Quality Declaration

This package claims to be in the Quality Level 1 category, see the Quality Declaration for more details.

Usage

The interface is provided through two classes, class_loader::ClassLoader and class_loader::MultiLibraryClassLoader. Both provide similar interfaces but the former only binds to a single runtime library whereas the latter can associate with multiple libraries. The typical workflow is as follows:

• Include class_loader/class_loader.h in your source code

• Instantiate a class_loader::ClassLoader object passing the path and name of the library to open

  class_loader::ClassLoader loader("libMyLibrary.so");
  

• Query the class for exported classes which have an interface defined by some base class (MyBase in the example)

  std::vector<std::string> classes = loader.getAvailableClasses<MyBase>()
  

• Create/destroy objects of said exported classes

  for(unsigned int c = 0; c < classes.size(); ++c)
  {
    boost::shared_ptr<MyBase> plugin = loader.createInstance<MyBase>(classes[c]);
    plugin->someMethod();
    //'plugin' will automatically be deleted when it goes out of scope
  }
  

• Destroy the ClassLoader object to shutdown the library.

Example: Basic Workflow for ClassLoader

#include <class_loader/class_loader.h>
#include "MyBase.h" //Defines class MyBase

int main()
{
  class_loader::ClassLoader loader("libMyLibrary.so");
  std::vector<std::string> classes = loader.getAvailableClasses<MyBase>();
  for(unsigned int c = 0; c < classes.size(); ++c)
  {
    boost::shared_ptr<MyBase> plugin = loader.createInstance<MyBase>(classes[c]);
    plugin->someMethod();
  }
}

Visit the class_loader API documentation for a complete list of its main components.

Page Hierarchy

• • QUALITY_DECLARATION

Class Hierarchy

• • Namespace class_loader
    • Namespace class_loader::impl
      • Template Class AbstractMetaObject
      • Class AbstractMetaObjectBase
      • Template Class MetaObject
      • Class MetaObjectGraveyardVector
    • Class ClassLoader
    • Class ClassLoaderException
    • Class CreateClassException
    • Class LibraryLoadException
    • Class LibraryUnloadException
    • Class MultiLibraryClassLoader
    • Class NoClassLoaderExistsException

File Hierarchy

• • Directory include
    • Directory class_loader
      • File class_loader.hpp
      • File class_loader_core.hpp
      • File exceptions.hpp
      • File meta_object.hpp
      • File multi_library_class_loader.hpp
      • File register_macro.hpp
      • File visibility_control.hpp
  • File QUALITY_DECLARATION.md
  • File README.md

Full C++ API

Namespaces

• Namespace class_loader

• Namespace class_loader::impl

• Namespace std

Classes and Structs

• Class ClassLoader

• Class ClassLoaderException

• Class CreateClassException

• Template Class AbstractMetaObject

• Class AbstractMetaObjectBase

• Template Class MetaObject

• Class MetaObjectGraveyardVector

• Class LibraryLoadException

• Class LibraryUnloadException

• Class MultiLibraryClassLoader

• Class NoClassLoaderExistsException

Functions

• Template Function class_loader::impl::createInstance

• Function class_loader::impl::getAllLibrariesUsedByClassLoader

• Template Function class_loader::impl::getAvailableClasses

• Function class_loader::impl::getCurrentlyActiveClassLoader

• Function class_loader::impl::getCurrentlyLoadingLibraryName

• Function class_loader::impl::getFactoryMapForBaseClass(const std::string&)

• Template Function class_loader::impl::getFactoryMapForBaseClass()

• Function class_loader::impl::getGlobalPluginBaseToFactoryMapMap

• Function class_loader::impl::getLoadedLibraryVector

• Function class_loader::impl::getLoadedLibraryVectorMutex

• Function class_loader::impl::getMetaObjectGraveyard

• Function class_loader::impl::getPluginBaseToFactoryMapMapMutex

• Function class_loader::impl::hasANonPurePluginLibraryBeenOpened()

• Function class_loader::impl::hasANonPurePluginLibraryBeenOpened(bool)

• Function class_loader::impl::isLibraryLoaded

• Function class_loader::impl::isLibraryLoadedByAnybody

• Function class_loader::impl::loadLibrary

• Function class_loader::impl::printDebugInfoToScreen

• Template Function class_loader::impl::registerPlugin

• Function class_loader::impl::setCurrentlyActiveClassLoader

• Function class_loader::impl::setCurrentlyLoadingLibraryName

• Function class_loader::impl::unloadLibrary

• Function class_loader::systemLibraryFormat

Defines

• Define CLASS_LOADER_EXPORT

• Define CLASS_LOADER_IMPORT

• Define CLASS_LOADER_LOCAL

• Define CLASS_LOADER_PUBLIC

• Define CLASS_LOADER_PUBLIC_TYPE

• Define CLASS_LOADER_REGISTER_CLASS

• Define CLASS_LOADER_REGISTER_CLASS_INTERNAL_HOP1_WITH_MESSAGE

• Define CLASS_LOADER_REGISTER_CLASS_INTERNAL_WITH_MESSAGE

• Define CLASS_LOADER_REGISTER_CLASS_WITH_MESSAGE

Typedefs

• Typedef class_loader::ClassLoaderVector

• Typedef class_loader::impl::BaseClassName

• Typedef class_loader::impl::BaseToFactoryMapMap

• Typedef class_loader::impl::ClassName

• Typedef class_loader::impl::DeleterType

• Typedef class_loader::impl::FactoryMap

• Typedef class_loader::impl::LibraryPair

• Typedef class_loader::impl::LibraryPath

• Typedef class_loader::impl::LibraryVector

• Typedef class_loader::impl::MetaObjectVector

• Typedef class_loader::impl::UniquePtr

• Typedef class_loader::LibraryPath

• Typedef class_loader::LibraryToClassLoaderMap

Directories

• Directory include

• Directory class_loader

Files

• File class_loader.hpp

• File class_loader_core.hpp

• File exceptions.hpp

• File meta_object.hpp

• File multi_library_class_loader.hpp

• File QUALITY_DECLARATION.md

• File README.md

• File register_macro.hpp

• File visibility_control.hpp

Pages

• QUALITY_DECLARATION