Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. Abstract plugin inheritance error
Forum Update on Monday, May 27th 2025

Abstract plugin inheritance error

Scheduled Pinned Locked Moved Solved General and Desktop
23 Posts 4 Posters 6.6k Views
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • 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.

    Interested in AI ? www.idiap.ch
    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

      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
      0
      • 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.

        Interested in AI ? www.idiap.ch
        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

            D 1 Reply Last reply
            0
            • 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

                    1 Reply Last reply
                    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 ♥

                      1 Reply Last reply
                      0

                      • Login

                      • Login or register to search.
                      • First post
                        Last post
                      0
                      • Categories
                      • Recent
                      • Tags
                      • Popular
                      • Users
                      • Groups
                      • Search
                      • Get Qt Extensions
                      • Unsolved