Hello all,

I've been following the docs for developing a plugin for my Qt application, using the low-level approach, as well as the plug & paint example. For whatever reason, when I run my application, it detects the plugin files but cannot generate an instance from them. Here's what I've got (using a single plugin as an example, and the relevant sections of my application).

First, I'll start with my interface, input.h:
Qt Code: 
  1. #ifndef INPUT_H
  2. #define INPUT_H
  3.  
  4. #       include <QObject>
  5.  
  6. class QPoint;
  7.  
  8. class input
  9. {
  10. Q_OBJECT
  11. public:
  12.         input() : allow(true){}
  13.         virtual ~input(){}
  14.  
  15.         virtual const QString getName()const = 0;
  16.         virtual const QString getDescription()const = 0;
  17. public slots:
  18.         virtual void setAllow(bool allow) = 0;
  19. signals:
  20.         void menuUp();
  21.         void menuDown();
  22.         void menuLeft();
  23.         void menuRight();
  24.         void tap(const QPoint & p);
  25. protected:
  26.         bool allow;
  27. };
  28.  
  29. Q_DECLARE_INTERFACE(input,
  30.                     "com.warfaresdl.evilcpc.input/1.0.0")
  31.  
  32. #endif
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And below, a sample input plugin, inputvoice.h:
Qt Code: 
  1. #ifndef INPUTVOICE_H
  2. #define INPUTVOICE_H
  3.  
  4. #       include <input.h>
  5.  
  6. class inputVoice : public input, public QObject
  7. {
  8. Q_OBJECT
  9. Q_INTERFACES(input)
  10. public:
  11.         inputVoice(QObject * p = 0);
  12.         virtual ~inputVoice();
  13.  
  14.         virtual const QString getName()const;
  15.         virtual const QString getDescription()const;
  16. public slots:
  17.         virtual void setAllow(const bool allow);
  18. };
  19.  
  20. #endif
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... and its implementation, inputVoice.cpp:
Qt Code: 
  1. #include "inputVoice.h"
  2. #include <QtPlugin>
  3.  
  4. inputVoice::inputVoice(QObject * p) : input(), QObject(p)
  5. {
  6. }
  7.  
  8. inputVoice::~inputVoice()
  9. {
  10. }
  11.  
  12. const QString inputVoice::getName()const
  13. {
  14.         return tr("Voice");
  15. }
  16.  
  17. const QString inputVoice::getDescription()const
  18. {
  19.         return tr("Voice input plugin");
  20. }
  21.  
  22. void inputVoice::setAllow(const bool a)
  23. {
  24.         allow = a;
  25. }
  26.  
  27. Q_EXPORT_PLUGIN2(inputVoice, inputVoice)
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The qmake .pro file for this plugin (voice):
Qt Code: 
  1. TEMPLATE        = lib
  2. HEADERS         = inputVoice.h
  3. SOURCES         = inputVoice.cpp
  4. VERSION         = 1.0.0
  5. CONFIG          = plugin debug_and_release qt
  6. QT              = core
  7. INCLUDEPATH     = ../interface
  8.  
  9. CONFIG(debug, debug|release) {
  10.         TARGET = inputVoice_debug
  11. } else {
  12.         TARGET = inputVoice
  13. }
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This generates a file, libinputVoice.so, which I sym-link to my application's project directory under a "plugins" sub-folder. My application uses the following qmake project file:
Qt Code: 
  1. CONFIG          = debug_and_release qt warn_on thread
  2. QT              = core
  3. TEMPLATE        = app
  4. HEADERS         =
  5. SOURCES         = main.cpp
  6. INCLUDEPATH     = ../plugins/menu/interface \
  7.                   ../plugins/menuItem/interface \
  8.                   ../plugins/input/interface
  9. LIBS            += -lmenu \
  10.                    -lpanel \
  11.                    -lncurses
  12.  
  13. CONFIG(debug, debug|release) {
  14.         TARGET = evilcpcconf-debug
  15. } else {
  16.         TARGET = evilcpcconf
  17. }
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... and in my application code, I use the following to load the plugin (stderr has been redirected to error.log via freopen):
Qt Code: 
  1. unsigned int index;
  2.         //load plugins at this point...
  3.         QStringList lPluginName;
  4.         QStringList lPluginDescription;
  5.         QStringList lPluginFile;
  6.         QDir pluginsDir = QDir(QCoreApplication::applicationDirPath());
  7. #if defined(Q_OS_WIN)
  8.         if(pluginsDir.dirName().toLower() == "debug" || pluginsDir.dirName().toLower() == "release")
  9.         {
  10.                 pluginsDir.cdUp();
  11.         }
  12. #elif defined(Q_OS_MAC)
  13.         if(pluginsDir.dirName() == "MacOS")
  14.         {
  15.                 pluginsDir.cdUp();
  16.                 pluginsDir.cdUp();
  17.                 pluginsDir.cdUp();
  18.         }
  19. #endif
  20.         cerr << "Using plugin path: " << pluginsDir.absolutePath().toAscii().data() << endl;
  21.         pluginsDir.cd("plugins");
  22.         cerr << "Changed to: " << pluginsDir.absolutePath().toAscii().data() << endl;
  23.         foreach(QString fileName, pluginsDir.entryList(QDir::Files))
  24.         {
  25.                 cerr << "Found a file: " << pluginsDir.absoluteFilePath(fileName).toAscii().data() << endl;
  26.                 QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
  27.                 QObject * plugin = loader.instance();
  28.                 if(!plugin)
  29.                 {   // This is where each plugin is ending up
  30.                         cerr << fileName.toAscii().data() << " is not a valid plugin..." << endl;
  31.                 }
  32.                 else
  33.                 {
  34.                         cerr << fileName.toAscii().data() << " is a valid plugin" << endl;
  35.                         if(qobject_cast<input *>(plugin))
  36.                         {
  37.                                 cerr << fileName.toAscii().data() << " is an input plugin" << endl;
  38.                                 input * i = qobject_cast<input *>(plugin);
  39.                                 lPluginFile << fileName;
  40.                                 lPluginName << i->getName();
  41.                                 lPluginDescription << i->getDescription();
  42.                         }
  43.                 }
  44.         }
  45.         if(!lPluginName.size())
  46.         {
  47.                 return;
  48.         }
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... and the cerr output:
Qt Code: 
  1. Using plugin path: /home/rich/svn/evilcpc/trunk/evilcpcconf
  2. Changed to: /home/rich/svn/evilcpc/trunk/evilcpcconf/plugins
  3. Found a file: /home/rich/svn/evilcpc/trunk/evilcpcconf/plugins/libinputVoice.so
  4. libinputVoice.so is not a valid plugin...
  5. Found a file: /home/rich/svn/evilcpc/trunk/evilcpcconf/plugins/libmenuAeon.so
  6. libmenuAeon.so is not a valid plugin...
  7. Found a file: /home/rich/svn/evilcpc/trunk/evilcpcconf/plugins/libmenuBasic.so
  8. libmenuBasic.so is not a valid plugin...
  9. Found a file: /home/rich/svn/evilcpc/trunk/evilcpcconf/plugins/libmenuItemGps.so
  10. libmenuItemGps.so is not a valid plugin...
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What am I doing incorrectly in my plugin code?