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Abstract plugin inheritance error

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  • SGaistS SGaist

    Hi,

    The usual setup when building a plugin based application is to have the plugin interfaces definitions and related code in a library that you will link to both the plugin and the application.

    That's what is suggested here.

    D Offline
    D Offline
    Defohin
    wrote on last edited by
    #13

    @SGaist I'm really struggling to understand, can you provide an example, please?

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by SGaist
      #14

      Roughly :
      pluginfoo.pro

      QT          += core gui
      TARGET       = pluginfoo
      TEMPLATE     = lib
      CONFIG      += plugin
      DESTDIR      = $$OUTPWD/bin/plugins
      LIBS += -L$$OUTPWD/lib -lmycoollib
      DEFINES     += QT_DEPRECATED_WARNINGS
      INCLUDEPATH += ../mycoollib
      SOURCES     += pluginfoo.cpp
      HEADERS     += pluginfoo.hpp
      DISTFILES   += pluginfoo.json
      

      mycoollib.pro

      QT          += core gui
      TARGET       = mycoollib
      TEMPLATE  = lib
      DESTDIR      = $$OUTPWD/lib
      INCLUDEPATH += .
      SOURCES     += \
          abstractplugin.cpp
      HEADERS     += \
          plugininterface.hpp
          abstractplugin.hpp
      
      

      myproject.pro

      QT      += core gui widgets xml network
      TARGET   = myproject
      TEMPLATE = app
      DESTDIR  = $$OUTPWD/bin
      LIBS += -L$$OUTPWD/lib -lmycoollib
      INCLUDEPATH += ../mycoollib
      DEFINES += QT_DEPRECATED_WARNINGS
      SOURCES += src/main.cpp \
                 gui/myprojectwindow.cpp
      
      HEADERS += gui/myprojectwindow.hpp
      

      Project structure

      mycoolproject \
      ---- mycoollib
      ---- pluginfoo
      ---- myproject
      

      mycoolproject being a SUBDIR project building first mycoollib and then pluginfoo and myproject.

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      1
      • SGaistS SGaist

        Roughly :
        pluginfoo.pro

        QT          += core gui
        TARGET       = pluginfoo
        TEMPLATE     = lib
        CONFIG      += plugin
        DESTDIR      = $$OUTPWD/bin/plugins
        LIBS += -L$$OUTPWD/lib -lmycoollib
        DEFINES     += QT_DEPRECATED_WARNINGS
        INCLUDEPATH += ../mycoollib
        SOURCES     += pluginfoo.cpp
        HEADERS     += pluginfoo.hpp
        DISTFILES   += pluginfoo.json
        

        mycoollib.pro

        QT          += core gui
        TARGET       = mycoollib
        TEMPLATE  = lib
        DESTDIR      = $$OUTPWD/lib
        INCLUDEPATH += .
        SOURCES     += \
            abstractplugin.cpp
        HEADERS     += \
            plugininterface.hpp
            abstractplugin.hpp
        
        

        myproject.pro

        QT      += core gui widgets xml network
        TARGET   = myproject
        TEMPLATE = app
        DESTDIR  = $$OUTPWD/bin
        LIBS += -L$$OUTPWD/lib -lmycoollib
        INCLUDEPATH += ../mycoollib
        DEFINES += QT_DEPRECATED_WARNINGS
        SOURCES += src/main.cpp \
                   gui/myprojectwindow.cpp
        
        HEADERS += gui/myprojectwindow.hpp
        

        Project structure

        mycoolproject \
        ---- mycoollib
        ---- pluginfoo
        ---- myproject
        

        mycoolproject being a SUBDIR project building first mycoollib and then pluginfoo and myproject.

        D Offline
        D Offline
        Defohin
        wrote on last edited by
        #15

        @SGaist Do I have to link with -l every single plugin I have? Or I can just provide a path like -L and it's going to work?

        I will try to modify here based on your example.

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by SGaist
          #16

          You don't link the plugins. You link your plugins against that common library.

          Yes, you have to use both -land -L.

          -L just tells the linker where to look at.

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          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          D 1 Reply Last reply
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          • SGaistS SGaist

            You don't link the plugins. You link your plugins against that common library.

            Yes, you have to use both -land -L.

            -L just tells the linker where to look at.

            D Offline
            D Offline
            Defohin
            wrote on last edited by
            #17

            @SGaist It works, but I have another question now.

            I named the "commonlib" to "pluginmanager" this class will hold information about plugins, load, unload and so on using QPluginLoader, but... when I try to use it on the main application including the header pluginmanager.hpp it says that it cannot open the file, even if I have the INCLUDEPATH += ../pluginmanager. On Qt Creator it does work, I'm able to ctrl+click, etc, but when I try to compile I get this error.

            jsulmJ 1 Reply Last reply
            0
            • D Defohin

              @SGaist It works, but I have another question now.

              I named the "commonlib" to "pluginmanager" this class will hold information about plugins, load, unload and so on using QPluginLoader, but... when I try to use it on the main application including the header pluginmanager.hpp it says that it cannot open the file, even if I have the INCLUDEPATH += ../pluginmanager. On Qt Creator it does work, I'm able to ctrl+click, etc, but when I try to compile I get this error.

              jsulmJ Offline
              jsulmJ Offline
              jsulm
              Lifetime Qt Champion
              wrote on last edited by jsulm
              #18

              @Defohin Did you run qmake again after changing the pro file? After qmake you should do a complete rebuild.

              https://forum.qt.io/topic/113070/qt-code-of-conduct

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              • jsulmJ jsulm

                @Defohin Did you run qmake again after changing the pro file? After qmake you should do a complete rebuild.

                D Offline
                D Offline
                Defohin
                wrote on last edited by
                #19

                @jsulm It works, but now I'm getting unresolved external symbol on the main project when trying to use PluginManager manager on the MyProjectWindow, and I have LIBS += -L../libs -lpluginmanager on the pro file.

                myprojectwindow.obj:-1: error: LNK2019: unresolved external symbol "public: __cdecl PluginManager::PluginManager(class QObject *)" (??0PluginManager@@QEAA@PEAVQObject@@@Z) referenced in function "public: __cdecl MyProjectWindow::MyProjectWindow(class QWidget *)" (??0MyProjectWindow@@QEAA@PEAVQWidget@@@Z)

                jsulmJ 1 Reply Last reply
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                • D Defohin

                  @jsulm It works, but now I'm getting unresolved external symbol on the main project when trying to use PluginManager manager on the MyProjectWindow, and I have LIBS += -L../libs -lpluginmanager on the pro file.

                  myprojectwindow.obj:-1: error: LNK2019: unresolved external symbol "public: __cdecl PluginManager::PluginManager(class QObject *)" (??0PluginManager@@QEAA@PEAVQObject@@@Z) referenced in function "public: __cdecl MyProjectWindow::MyProjectWindow(class QWidget *)" (??0MyProjectWindow@@QEAA@PEAVQWidget@@@Z)

                  jsulmJ Offline
                  jsulmJ Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by
                  #20

                  @Defohin ../libs is a relative path, are you sure it is correct?
                  Can you post the compiler/linker call just before the error message?
                  As suggested by @SGaist : LIBS += -L$$OUTPWD/lib -lmycoollib (pluginmanager instead of mycoollib)

                  https://forum.qt.io/topic/113070/qt-code-of-conduct

                  D 1 Reply Last reply
                  0
                  • jsulmJ jsulm

                    @Defohin ../libs is a relative path, are you sure it is correct?
                    Can you post the compiler/linker call just before the error message?
                    As suggested by @SGaist : LIBS += -L$$OUTPWD/lib -lmycoollib (pluginmanager instead of mycoollib)

                    D Offline
                    D Offline
                    Defohin
                    wrote on last edited by
                    #21

                    @jsulm I'm using $$OUTPWD now but it still doesn't work.

                    jsulmJ 1 Reply Last reply
                    0
                    • D Defohin

                      @jsulm I'm using $$OUTPWD now but it still doesn't work.

                      jsulmJ Offline
                      jsulmJ Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by
                      #22

                      @Defohin Is the resulting path correct and is the lib there?

                      https://forum.qt.io/topic/113070/qt-code-of-conduct

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                      • D Offline
                        D Offline
                        Defohin
                        wrote on last edited by Defohin
                        #23

                        It's working now, I forgot to put MYPROJECT_EXPORT on PluginManager class.

                        I love you guys ♥

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