QPluginLoader cannot load plugin [solved]

[alex_malyu]

There are many possible sources of problem - from poorly written plugin to plugin built with different toolchain or different CRT.

[GrahamL]

Hi
I found this link useful
http://canvoki.net/Codders/qtpluginnotloading.html

HTH

[LeaA]

@SGaist

thank you for the answer..
yes, I called thia macro in the class that implements the plugin interface and then I got many errors like this:
error: undefined reference to vtable for InPluginInterface' error: undefined reference to InPluginInterface::metaObject() const'
error: undefined reference to `InPluginInterface::qt_metacast(char const*)'

etc. ....

the plugin is not for qt creator, its for a project that i do with qt creator

[LeaA]

@GrahamL

this link useful for plugins for widgets..

my plugin isn't for widget...

[GrahamL]

@LeaA

Its hard to guess without seeing your code
Is it possible for you to share your class definitions?

[LeaA]

why is the QLibraryPrivate::IsNotAPlugin (1)????

[LeaA]

here is the code:

the h file of the interface:

#ifndef INPLUGININTERFACE_H
#define INPLUGININTERFACE_H
#pragma once

#include <QtPlugin>
#include <QObject>
#include <QtCore>

#include "ProcessingInterface.h"
#include "setting.h"
#include "msstorage.h"
#include "myplot.h"

/**
@brief The InPluginInterface class
Factory of prossesingInterface
/
class InPluginInterface//:public QObject
{
// Q_OBJECT
public:
virtual ~InPluginInterface() = default;
virtual std::shared_ptr <ProcessingInterface> getProcessing
(myPlotInterface& plot,
QVector<ReducingInterface> reduceData)=0;
};

Q_DECLARE_INTERFACE(InPluginInterface,"InPluginImp")

#endif // INPLUGININTERFACE_H

the h file of the class that implements the plugin:

#ifndef INPLUGINIMP_H
#define INPLUGINIMP_H

#include <QtScript/QScriptEngine>
#include <QtScript/QScriptValue>
#include <memory>

#include "inPluginInterface.h"
#include "ProcessingInterface.h"
#include "impprocessing.h"

class Q_DECL_EXPORT InPluginImp :public QObject,public InPluginInterface
{
//Q_OBJECT
Q_PLUGIN_METADATA(IID "InPluginImp")
Q_INTERFACES(InPluginInterface)

public:
InPluginImp();

~InPluginImp()=default;

// InPluginInterface interface

std::shared_ptr<ProcessingInterface> getProcessing
(myPlotInterface &plot,
 QVector<ReducingInterface *> msStorages) override;

};

#endif // INPLUGINIMP_H

the cpp file:

#include "inpluginimp.h"

InPluginImp::InPluginImp()
{

}

std::shared_ptr <ProcessingInterface> InPluginImp::getProcessing
( myPlotInterface& plot,
QVector<ReducingInterface*> msStorages)

{
std::shared_ptr <ProcessingInterface> p=std::make_shared<impProcessing>(plot ,msStorages);
return p;
}

the function that loading the plugin:

void Manager::loadPlugins()
{
pluginsDir = QDir(qApp->applicationDirPath());

#if defined(Q_OS_WIN)
if (pluginsDir.dirName().toLower() == "debug" || pluginsDir.dirName().toLower() == "release")
pluginsDir.cdUp();
#elif defined(Q_OS_MAC)
if (pluginsDir.dirName() == "MacOS") {
pluginsDir.cdUp();
pluginsDir.cdUp();
pluginsDir.cdUp();
}
#endif
//search the file that there the plugin declared
pluginsDir.cd("plugins");

foreach (QString fileName, pluginsDir.entryList(QDir::Files)) {
    QPluginLoader loader(pluginsDir.absoluteFilePath(fileName));
  
    QObject *plugin = loader.instance();

    if (plugin) {

        pluginFileNames += fileName;

    }
}

}

what is the problem here? why the QPluginLoader doesn't load the plugin? why the QLibraryPrivate::IsNotAPlugin (1)????

thanks!

[LeaA]

the problem solved

[GrahamL]

Hi
What was the problem and how did you solve it?

[LeaA]

@GrahamL

the problem was that the plugin wasn't created good and the QPluginLoader wasn't recognized it as a plugin.

i returned the macro Q_OBJECT to InPluginImp class and i moved the inheritance from QOBJECT to the InPluginInterface class.

[GrahamL]

Ah
Please mark the topic as SOLVED
Thanks

[LeaA]

hi,
now i getting this error:
C:\workspace\16-5-15\src\mainProject\build-mainProject-Desktop_Qt_5_3_MinGW_32bit-Debug\VisualReceiverErrorsAnalysis\debug\moc_inpluginimp.cpp:149: error: undefined reference to `InPluginImp::InPluginImp()'

and this one:
moc_inpluginimp.cpp:-1: error: undefined reference to `InPluginImp::getProcessing(myPlotInterface&, QVector<ReducingInterface*>)'

collect2.exe:-1: error: error: ld returned 1 exit status

there is a solution for it?..

[SGaist]

Did you properly implement both these functions ? Do you build the corresponding cpp file ?

[LeaA]

@SGaist

yes..

[LeaA]

@SGaist

it seems like a problem with the moc.cpp file of inpluginimp

[LeaA]

when i putting down the Q_OBJECT macro from the inPluginImp class the errors gone but the again the first problem in this topic comming back

[SGaist]

When adding/removing the Q_OBJECT macro, do you re-run qmake before building ?

[LeaA]

@SGaist

yes

[LeaA]

@SGaist

it says to me that the moc_inpluginimp.cpp file isn't found..
but the file is in the build directory of the project in the debuge directory

[jalomic]

@LeaA said:

#ifndef INPLUGININTERFACE_H
#define INPLUGININTERFACE_H
#pragma once
.....
.....
#endif // INPLUGININTERFACE_H

T_T WTF ?