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 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.
This package claims to be in the Quality Level 1 category, see the Quality Declaration for more details.
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.hin your source code - Instantiate a
class_loader::ClassLoaderobject 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.
#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.
