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tdelibs/kdecore/klibloader.h

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/* This file is part of the KDE libraries
Copyright (C) 1999 Torben Weis <weis@kde.org>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License version 2 as published by the Free Software Foundation.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#ifndef KLIBLOADER_H
#define KLIBLOADER_H
#include <qobject.h>
#include <qstring.h>
#include <qstringlist.h>
#include <qasciidict.h>
#include <qptrlist.h>
#include <kglobal.h>
#include <stdlib.h> // For backwards compatibility
class KInstance;
class QTimer;
class KLibrary;
class KLibFactory;
class KLibFactoryPrivate;
class KLibLoaderPrivate;
class KLibraryPrivate;
# define K_EXPORT_COMPONENT_FACTORY( libname, factory ) \
extern "C" { KDE_EXPORT void *init_##libname() { return new factory; } }
/**
* @short Represents a dynamically loaded library.
*
* KLibrary allows you to look up symbols of the shared library.
* Use KLibLoader to create a new instance of KLibrary.
*
* @see KLibLoader
* @author Torben Weis <weis@kde.org>
*/
class KDECORE_EXPORT KLibrary : public QObject
{
friend class KLibLoader;
friend class QAsciiDict<KLibrary>;
Q_OBJECT
public:
/**
* Don't create KLibrary objects on your own. Instead use KLibLoader.
*/
KLibrary( const QString& libname, const QString& filename, void * handle );
/**
* Returns the name of the library.
* @return The name of the library like "libkspread".
*/
QString name() const;
/**
* Returns the file name of the library.
* @return The filename of the library, for example "/opt/kde2&/lib/libkspread.la"
*/
QString fileName() const;
/**
* Returns the factory of the library.
* @return The factory of the library if there is any, otherwise 0
*/
KLibFactory* factory();
/**
* Looks up a symbol from the library. This is a very low level
* function that you usually don't want to use. Usually you should
* check using hasSymbol() whether the symbol actually exists,
* otherwise a warning will be printed.
* @param name the name of the symbol to look up
* @return the address of the symbol, or 0 if it does not exist
* @see hasSymbol
*/
void* symbol( const char* name ) const;
/**
* Looks up a symbol from the library. This is a very low level
* function that you usually don't want to use.
* Unlike symbol(), this method doesn't warn if the symbol doesn't exist,
* so if the symbol might or might not exist, better use hasSymbol() before symbol().
* @param name the name of the symbol to check
* @return true if the symbol exists
* @since 3.1
*/
bool hasSymbol( const char* name ) const;
/**
* Unloads the library.
* This typically results in the deletion of this object. You should
* not reference its pointer after calling this function.
*/
void unload() const;
private slots:
void slotObjectCreated( QObject *obj );
void slotObjectDestroyed();
void slotTimeout();
private:
/**
* @internal
* Don't destruct KLibrary objects yourself. Instead use unload() instead.
*/
~KLibrary();
QString m_libname;
QString m_filename;
KLibFactory* m_factory;
void * m_handle;
QPtrList<QObject> m_objs;
QTimer *m_timer;
KLibraryPrivate *d;
};
class KLibWrapPrivate;
/**
* The KLibLoader allows you to load libraries dynamically at runtime.
* Dependent libraries are loaded automatically.
*
* KLibLoader follows the singleton pattern. You can not create multiple
* instances. Use self() to get a pointer to the loader.
*
* @see KLibrary
* @author Torben Weis <weis@kde.org>
*/
class KDECORE_EXPORT KLibLoader : public QObject
{
friend class KLibrary;
Q_OBJECT
public:
/**
* You should NEVER destruct an instance of KLibLoader
* until you know what you are doing. This will release
* the loaded libraries.
*/
~KLibLoader();
/**
* Loads and initializes a library. Loading a library multiple times is
* handled gracefully.
*
* This is a convenience function that returns the factory immediately
* @param libname This is the library name without extension. Usually that is something like
* "libkspread". The function will then search for a file named
* "libkspread.la" in the KDE library paths.
* The *.la files are created by libtool and contain
* important information especially about the libraries dependencies
* on other shared libs. Loading a "libfoo.so" could not solve the
* dependencies problem.
*
* You can, however, give a library name ending in ".so"
* (or whatever is used on your platform), and the library
* will be loaded without resolving dependencies. Use with caution.
* @return the KLibFactory, or 0 if the library does not exist or it does
* not have a factory
* @see library
*/
KLibFactory* factory( const char* libname );
/**
* Loads and initializes a library. Loading a library multiple times is
* handled gracefully.
*
* @param libname This is the library name without extension. Usually that is something like
* "libkspread". The function will then search for a file named
* "libkspread.la" in the KDE library paths.
* The *.la files are created by libtool and contain
* important information especially about the libraries dependencies
* on other shared libs. Loading a "libfoo.so" could not solve the
* dependencies problem.
*
* You can, however, give a library name ending in ".so"
* (or whatever is used on your platform), and the library
* will be loaded without resolving dependencies. Use with caution.
* @return KLibrary is invalid (0) when the library couldn't be dlopened. in such
* a case you can retrieve the error message by calling KLibLoader::lastErrorMessage()
*
* @see factory
*/
virtual KLibrary* library( const char* libname );
/**
* Loads and initializes a library. Loading a library multiple times is
* handled gracefully. The library is loaded such that the symbols are
* globally accessible so libraries with dependencies can be loaded
* sequentially.
*
* @param name This is the library name without extension. Usually that is something like
* "libkspread". The function will then search for a file named
* "libkspread.la" in the KDE library paths.
* The *.la files are created by libtool and contain
* important information especially about the libraries dependencies
* on other shared libs. Loading a "libfoo.so" could not solve the
* dependencies problem.
*
* You can, however, give a library name ending in ".so"
* (or whatever is used on your platform), and the library
* will be loaded without resolving dependencies. Use with caution.
* @return KLibrariy is invalid (0) when the library couldn't be dlopened. in such
* a case you can retrieve the error message by calling KLibLoader::lastErrorMessage()
*
* @see factory
*/
KLibrary* globalLibrary( const char *name );
/**
* Returns an error message that can be useful to debug the problem.
* Returns QString::null if the last call to library() was successful.
* You can call this function more than once. The error message is only
* reset by a new call to library().
* @return the last error message, or QString::null if there was no error
*/
QString lastErrorMessage() const;
/**
* Unloads the library with the given name.
* @param libname This is the library name without extension. Usually that is something like
* "libkspread". The function will then search for a file named
* "libkspread.la" in the KDE library paths.
* The *.la files are created by libtool and contain
* important information especially about the libraries dependencies
* on other shared libs. Loading a "libfoo.so" could not solve the
* dependencies problem.
*
* You can, however, give a library name ending in ".so"
* (or whatever is used on your platform), and the library
* will be loaded without resolving dependencies. Use with caution.
*/
virtual void unloadLibrary( const char *libname );
/**
* Returns a pointer to the factory. Use this function to get an instance
* of KLibLoader.
* @return a pointer to the loader. If no loader exists until now
* then one is created.
*/
static KLibLoader* self();
/**
* @internal
* Internal Method, called by the KApplication destructor.
* Do not call it.
* This is what makes it possible to rely on ~KLibFactory
* being called in all cases, whether the library is unloaded
* while the application is running or when exiting.
*/
static void cleanUp();
/**
* Helper method which looks for a library in the standard paths
* ("module" and "lib" resources).
* Made public for code that doesn't use KLibLoader itself, but still
* wants to open modules.
* @param name of the library. If it is not a path, the function searches in
* the "module" and "lib" resources. If there is no extension,
* ".la" will be appended.
* @param instance a KInstance used to get the standard paths
*/
static QString findLibrary( const char * name, const KInstance * instance = KGlobal::instance() );
protected:
KLibLoader( QObject* parent = 0, const char* name = 0 );
private slots:
void slotLibraryDestroyed();
private:
void close_pending( KLibWrapPrivate * );
QAsciiDict<KLibWrapPrivate> m_libs;
static KLibLoader* s_self;
protected:
virtual void virtual_hook( int id, void* data );
private:
KLibLoaderPrivate *d;
};
/**
* If you develop a library that is to be loaded dynamically at runtime, then
* you should return a pointer to your factory. The K_EXPORT_COMPONENT_FACTORY
* macro is provided for this purpose:
* \code
* K_EXPORT_COMPONENT_FACTORY( libkspread, KSpreadFactory )
* \endcode
*
* The first macro argument is the name of your library, the second specifies the name
* of your factory.
*
* NOTE: you probably want to use KGenericFactory<PluginClassName>
* instead of writing your own factory.
*
* In the constructor of your factory you should create an instance of KInstance
* like this:
* \code
* s_global = new KInstance( "kspread" );
* \endcode
* This KInstance is comparable to KGlobal used by normal applications.
* It allows you to find resource files (images, XML, sound etc.) belonging
* to the library.
*
* If you want to load a library, use KLibLoader. You can query KLibLoader
* directly for a pointer to the libraries factory by using the KLibLoader::factory()
* function.
*
* The KLibFactory is used to create the components, the library has to offer.
* The factory of KSpread for example will create instances of KSpreadDoc,
* while the Konqueror factory will create KonqView widgets.
* All objects created by the factory must be derived from QObject, since QObject
* offers type safe casting.
*
* KLibFactory is an abstract class. Reimplement the
* createObject() method to give it functionality.
*
* @author Torben Weis <weis@kde.org>
*/
class KDECORE_EXPORT KLibFactory : public QObject
{
Q_OBJECT
public:
/**
* Create a new factory.
* @param parent the parent of the QObject, 0 for no parent
* @param name the name of the QObject, 0 for no name
*/
KLibFactory( QObject* parent = 0, const char* name = 0 );
virtual ~KLibFactory();
/**
* Creates a new object. The returned object has to be derived from
* the requested classname.
*
* It is valid behavior to create different kinds of objects
* depending on the requested @p classname. For example a koffice
* library may usually return a pointer to KoDocument. But
* if asked for a "QWidget", it could create a wrapper widget,
* that encapsulates the Koffice specific features.
*
* create() automatically emits a signal objectCreated to tell
* the library about its newly created object. This is very
* important for reference counting, and allows unloading the
* library automatically once all its objects have been destroyed.
*
* @param parent the parent of the QObject, 0 for no parent
* @param name the name of the QObject, 0 for no name
* @param classname the name of the class
* @param args a list of arguments
*/
QObject* create( QObject* parent = 0, const char* name = 0, const char* classname = "QObject", const QStringList &args = QStringList() );
signals:
/**
* Emitted in #create
* @param obj the new object
*/
void objectCreated( QObject *obj );
protected:
/**
* Creates a new object. The returned object has to be derived from
* the requested classname.
*
* It is valid behavior to create different kinds of objects
* depending on the requested @p className. For example a koffice
* library may usually return a pointer to KoDocument. But
* if asked for a "QWidget", it could create a wrapper widget,
* that encapsulates the Koffice specific features.
*
* This function is called by #create()
* @param parent the parent of the QObject, 0 for no parent
* @param name the name of the QObject, 0 for no name
* @param className the name of the class
* @param args a list of arguments
*/
virtual QObject* createObject( QObject* parent = 0, const char* name = 0,
const char* className = "QObject",
const QStringList &args = QStringList() ) = 0;
protected:
virtual void virtual_hook( int id, void* data );
private:
KLibFactoryPrivate *d;
};
#endif