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Abstract plugin inheritance error

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  • SGaistS Offline
    SGaistS Offline
    SGaist
    Lifetime Qt Champion
    wrote on last edited by
    #12

    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.

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    D 1 Reply Last reply
    1
    • 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?

      1 Reply Last reply
      0
      • 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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        D 1 Reply Last reply
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        • 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.

          1 Reply Last reply
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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
            1
            • 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
                  0
                  • 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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                        0
                        • 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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