Subclassing

This is a discussion on Subclassing within the C++ Programming forums, part of the General Programming Boards category; I'm working on a small gui project and I needed to subclass a form. Everything looks ok but when I ...

  1. #1
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    Subclassing

    I'm working on a small gui project and I needed to subclass a form. Everything looks ok but when I go and compile I'm getting the following error
    In function `AMainWindow::AMainWindow(QWidget *, char const *, unsigned int)':
    .obj/amainwindow.o(.text+0xb1): undefined reference to `AWorkspace virtual table'

    The subclass is called AWorkspace. Any pointers (no pun intended) in the right direction would be great.

    Thanks

  2. #2
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    we're going to need more info than that... paste some code or give a little more detail.

    looks like something to do with not specifying the body of a virtual function..
    that's just a guess though.
    Quidquid latine dictum sit, altum sonatur.
    Whatever is said in Latin sounds profound.

  3. #3
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    #ifndef AWORKSPACE_H
    #define AWORKSPACE_H

    #include <qworkspace.h>

    class AWorkspace : public QWorkspace
    {
    Q_OBJECT
    public:
    AWorkspace(QWidget *parent = 0, const char *name = 0) : QWorkspace(parent,name) {}

    ~AWorkspace() {}
    protected:
    void childEvent(QChildEvent *e);
    };

    #endif //AWORKSPACE_H

    This is all that there is. The errors that I was talking about simply came when I tried to create an instance of this class. The childEvent function is virtual in the base class. I also tried this with just the constructor and destructor and was running into the same issues.

  4. #4
    Registered User JasonLikesJava's Avatar
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    I'm getting the same error.... Everything was fine until I added the Q_OBJECT macro. I can do everything with my class when I take out the Q_OBJECT macro only I no longer have signals and slots.
    Last edited by JasonLikesJava; 05-30-2002 at 01:09 PM.
    OS: Linux Mandrake 9.0
    Compiler: gcc-3.2
    Languages: C, C++, Java

    If you go flying back through time and you see somebody else flying forward into the future, it's probably best to avoid eye contact.

  5. #5
    Registered User JasonLikesJava's Avatar
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    Hmm... I got my class working, although I'm not even sure what I changed exactly. Try removing all compiled objects and then compile it again including <qwidget.h>
    OS: Linux Mandrake 9.0
    Compiler: gcc-3.2
    Languages: C, C++, Java

    If you go flying back through time and you see somebody else flying forward into the future, it's probably best to avoid eye contact.

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