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Thread: Problems with the Q_OBJECT-Macro

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  1. #1
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    Default Problems with the Q_OBJECT-Macro

    Hello out there,
    I have so troubble building a small app. My main.cpp has this easy structur:
    #include "qtexplorer.h"

    #include <QtGui>
    #include <QApplication>
    #include <QPushButton>

    int main(int argc, char *argv[])
    {
    QApplication a(argc, argv);
    QtExplorer w = new QtExplorer;
    w.show();
    return a.exec();
    }

    my QtExplorer.h looks like this:
    #ifndef QTEXPLORER_H
    #define QTEXPLORER_H

    #include <QWidget>
    #include <QPushButton>
    #include <QVBoxLayout>
    #include "ui_qtexplorer.h"

    class QtExplorer : public QWidget
    {
    Q_OBJECT

    public:
    QtExplorer(QWidget *parent = 0);
    ~QtExplorer();

    private:
    Ui::QtExplorerClass ui;
    long req_id;
    private slots:
    int ReadRegister();
    int WriteRegister();
    int ReadMem();
    int WriteMem();
    };

    #endif // QTEXPLORER_H


    So, what is my problem? I cannot build this easy code because there is an error at the first curly brace in the qtexplorer.h (this comes of the eclipse integration plugin) which says: "within this context".
    After that brace comes the macro Q_OBJECT. Without this macro I cannot define slots. But what can I do to clear this error?

    Thank you in advance..

    Sincerely Tok

  2. #2
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    Default Re: Problems with the Q_OBJECT-Macro

    what the strange code
    Qt Code:
    1. ...
    2. QtExplorer w = new QtExplorer;
    3. w.show();
    4. ...
    To copy to clipboard, switch view to plain text mode 

    modify it
    Qt Code:
    1. ...
    2. QtExplorer w;
    3. w.show();
    4. ...
    To copy to clipboard, switch view to plain text mode 
    Qt Assistant -- rocks!
    please, use tags [CODE] & [/CODE].

  3. #3
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    Default Re: Problems with the Q_OBJECT-Macro

    Thanks now it works. But what is the difference? Why I cannot call it by the usual methode?

    Sincerely Tok

  4. #4
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    Default Re: Problems with the Q_OBJECT-Macro

    Qt Code:
    1. QtExplorer *w = new QtExplorer();
    2. w->show();
    3. delete w;
    To copy to clipboard, switch view to plain text mode 

    or

    Qt Code:
    1. QtExplorer w;
    2. w.show();
    To copy to clipboard, switch view to plain text mode 

    Once you create the object on the heap, once on the stack.
    Qt Code:
    1. QtExplorer w = new QtExplorer();
    To copy to clipboard, switch view to plain text mode 
    is just invalid code...

  5. #5
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    Default Re: Problems with the Q_OBJECT-Macro

    Okay thank you.
    The reason why I changed it to a new()-constructor is, that I cannot debug the small program. If I start the debugger (under Eclipse Qt-integration, Linux) I get the message "No symbol "new" in current context." on the eclipse-console. I thought this isn't serious but I tied with a new()-operator.
    I start debugging with the main-method (obvious) but if I jump to the construction point ( QtExplorer w; ) the sourcecode-window is closed with a message "No source available for "" " and if I go one step further, the whole execution stops with the message "Cannot find bounds of current function".

    What is the meaning of that? (I installed the libqt-dbg!)

    Thank you in advance

    Sincerely Tok
    Last edited by tokstolle; 23rd March 2009 at 15:45.

  6. #6
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    Default Re: Problems with the Q_OBJECT-Macro

    Ahhh, Im one step further.
    But now gdb on eclipse stucks with the message:
    Can't find a source file at "widgets/qlineedit.h"
    Locate the file or edit the source lookup path to include its location.
    So where should this source-code installed? I thought I have it all with the qt4-dev-package of debian?

    Thank you

    Sincerely Tok

  7. #7
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    Default Re: Problems with the Q_OBJECT-Macro

    a) did you use #include <QLineEdit>?
    b) Look, if under project->properties->C++ Include paths the right directories are set.

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