Library: Foundation
Package: SharedLibrary
Header: Poco/ClassLoader.h
The ClassLoader loads C++ classes from shared libraries at runtime. It must be instantiated with a root class of the loadable classes. For a class to be loadable from a library, the library must provide a Manifest of all the classes it contains. The Manifest for a shared library can be easily built with the help of the macros in the header file "Foundation/ClassLibrary.h".
Starting with POCO release 1.3, a class library can export multiple manifests. In addition to the default (unnamed) manifest, multiple named manifests can be exported, each having a different base class.
There is one important restriction: one instance of ClassLoader can only load one manifest from a class library.
Member Functions: begin, canCreate, classFor, create, destroy, end, findClass, findManifest, instance, isAutoDelete, isLibraryLoaded, loadLibrary, manifestFor, unloadLibrary
The ClassLoader's very own iterator class. 
typedef bool (* BuildManifestFunc)(ManifestBase *);
typedef void (* InitializeLibraryFunc)();
typedef std::map < std::string, LibraryInfo > LibraryMap;
typedef Manifest < Base > Manif;
typedef AbstractMetaObject < Base > Meta;
typedef void (* UninitializeLibraryFunc)();
ClassLoader();
Creates the ClassLoader.
virtual ~ClassLoader();
Destroys the ClassLoader.
Iterator begin() const;
bool canCreate(
const std::string & className
) const;
Returns true if create() can create new instances of the class.
const Meta & classFor(
const std::string & className
) const;
Returns a reference to the MetaObject for the given class. Throws a NotFoundException if the class is not known.
Base * create(
const std::string & className
) const;
Creates an instance of the given class. Throws a NotFoundException if the class is not known.
void destroy(
const std::string & className,
Base * pObject
) const;
Destroys the object pObject points to. Does nothing if object is not found.
Iterator end() const;
const Meta * findClass(
const std::string & className
) const;
Returns a pointer to the MetaObject for the given class, or a null pointer if the class is not known.
const Manif * findManifest(
const std::string & path
) const;
Returns a pointer to the Manifest for the given library, or a null pointer if the library has not been loaded.
Base & instance(
const std::string & className
) const;
Returns a reference to the sole instance of the given class. The class must be a singleton, otherwise an InvalidAccessException will be thrown. Throws a NotFoundException if the class is not known.
bool isAutoDelete(
const std::string & className,
Base * pObject
) const;
Returns true if the object is automatically deleted by its meta object.
bool isLibraryLoaded(
const std::string & path
) const;
Returns true if the library with the given name has already been loaded.
void loadLibrary(
const std::string & path,
const std::string & manifest
);
Loads a library from the given path, using the given manifest. Does nothing if the library is already loaded. Throws a LibraryLoadException if the library cannot be loaded or does not have a Manifest. If the library exports a function named "pocoInitializeLibrary", this function is executed. If called multiple times for the same library, the number of calls to unloadLibrary() must be the same for the library to become unloaded.
void loadLibrary(
const std::string & path
);
Loads a library from the given path. Does nothing if the library is already loaded. Throws a LibraryLoadException if the library cannot be loaded or does not have a Manifest. If the library exports a function named "pocoInitializeLibrary", this function is executed. If called multiple times for the same library, the number of calls to unloadLibrary() must be the same for the library to become unloaded.
Equivalent to loadLibrary(path, "").
const Manif & manifestFor(
const std::string & path
) const;
Returns a reference to the Manifest for the given library Throws a NotFoundException if the library has not been loaded.
void unloadLibrary(
const std::string & path
);
Unloads the given library. Be extremely cautious when unloading shared libraries. If objects from the library are still referenced somewhere, a total crash is very likely. If the library exports a function named "pocoUninitializeLibrary", this function is executed before it is unloaded. If loadLibrary() has been called multiple times for the same library, the number of calls to unloadLibrary() must be the same for the library to become unloaded.