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/* -*- c++ -*-
This file is part of libkdepim.
Copyright (c) 2002,2004 Marc Mutz <mutz@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 as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
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 __KPIM_SHARED_PLUGINLOADER_H__
#define __KPIM_SHARED_PLUGINLOADER_H__
#include <pluginloaderbase.h>
namespace KPIM {
/**
* @short A generic plugin loader for when KPart::Plugin is overkill
* @author Marc Mutz <mutz@kde.org> based on KABC's FormatFactory
*
* This is a generic plugin loader / factory for small plugins that
* don't want to be QObjects.
*
* @section Usage
*
* A PluginLoader takes two template arguments, <code>T</code> and
* <code>T_config</code>:
*
* <dl>
* <dt>T</dt><dd>The type of object to return</dd>
* <dt>T_config::mainfunc</dt><dd>The suffix of the factory function to call
* in the library to obtain a new object of type <code>T</code>.
* The string passed to <code>KLibrary::symbol()</code> is
* <code>libName_mainfunc</code>.</dd>
* <dt>T_config::path</dt><dd>The search pattern for <tt>.desktop</tt> files
* containing the plugin descriptions. This is the string passed as
* the @p filter argument to
* <code>KStandardDirs::findAllResources</code>.</dd>
* </dl>
*
* The last two parameters being strings, they are passed via an
* encapsulating class, of which <code>mainfunc</code> and
* <code>path</code> are public static members:
*
* <pre>
* struct MyObjectPluginLoaderConfig {
* static const char * const mainfunc;
* static const char * const path;
* };
* const char * const MyObjectPluginLoaderConfig::mainfunc = "myapp_create_myobject";
* const char * const MyObjectPluginLoaderConfig::path = "myapp/plugins/ *.desktop";
* </pre>
*
* You would then use a <tt>typedef</tt> to create a less unwieldy
* name for your plugin loader:
*
* <pre>
* typedef KPIM::PluginLoader< MyObject, MyObjectPluginLoaderConfig > MyObjectPluginLoader;
* </pre>
*
* All of this is what the
* <code>KPIM_DEFINE_PLUGIN_LOADER(pluginloadername,type,mainfunc,path)</code> macro
* achieves.
*
**/
template< typename T, typename T_config >
class KDE_EXPORT PluginLoader : public PluginLoaderBase {
protected:
PluginLoader() : PluginLoaderBase() {}
private:
static PluginLoader<T,T_config> * mSelf;
public:
virtual ~PluginLoader() { mSelf = 0; }
/** Returns the single instance of this loader. */
static PluginLoader<T,T_config> * instance() {
if ( !mSelf ) {
mSelf = new PluginLoader<T,T_config>();
mSelf->scan();
}
return mSelf;
}
/** Rescans the plugin directory to find any newly installed
plugins.
**/
virtual void scan() {
doScan( T_config::path );
}
/** Returns a pointer to a plugin object (of type @p T) or a null
pointer if the type wasn't found. You can extend this method
for when you want to handle builtin types */
virtual T * createForName( const QString & type ) const {
void * main_func = mainFunc( type, T_config::mainfunc );
if ( !main_func ) return 0;
// cast to a pointer to a function returning T*, call it and
// return the result; don't you love C? ;-)
return ((T* (*)())( main_func ))();
}
};
template< typename T, typename T_config >
PluginLoader<T,T_config> * PluginLoader<T,T_config>::mSelf = 0;
}
#define KPIM_DEFINE_PLUGIN_LOADER( pl, t, mf, p ) \
namespace { /* don't pollute namespaces */ \
struct KDE_EXPORT pl##Config { \
static const char * const mainfunc; \
static const char * const path; \
}; \
const char * const pl##Config::mainfunc = mf; \
const char * const pl##Config::path = p; \
} \
typedef KPIM::PluginLoader< t, pl##Config > pl; \
#endif // __KPIM_SHARED_PLUGINLOADER_H__
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