Defining a Qt plug-in interface
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Compatibility
S60 5th Edition
Article
Contents |
Overview
Qt applications can be extended with Qt plug-ins, which means that some of the application functionality is implemented as common plug-in libraries loaded into the application memory at runtime. To be extendable, the application has to define a common plug-in interface (exampleplugininterface.h). Note that the application does not see the plug-ins directly but only methods and data that are defined into the interface. The detection and loading of plug-ins is handled using QPluginLoader.
This code snippet demonstrates how to define the lower-level Qt plug-in interface. Implementing the interface and using the plug-in are described in additional snippet articles.
Header (exampleplugininterface.h)
The plug-in interface for all "example plug-ins". The plug-in must implement the virtual sayHello() method and the virtual someSlot() slot.
#include <QObject>
#include <QString>
class ExamplePluginInterface : public QObject
{
public:
virtual ~ExamplePluginInterface() {}
virtual QString sayHello() = 0;
public slots:
virtual void someSlot(QString value) = 0;
protected: // Common data for the plugins
QString data;
};
// This Qt macro associates the given Identifier
// "Forum.Nokia.wiki.pluginsnippet.ExamplePluginInterface/1.0"
// to the interface class called ExamplePluginInterface.
// The Identifier must be unique.
Q_DECLARE_INTERFACE(ExamplePluginInterface,
"Forum.Nokia.wiki.pluginsnippet.ExamplePluginInterface/1.0");
See also
- Implementing the Qt plug-in interface
- Loading and initialising a Qt plug-in dynamically
- For more information about, see How to Create Qt Plugins.
Postconditions
The Qt plug-in interface is defined.
