Program crashes (SIGSEGV)

[Voldemort]

@wysota:

1) What do you mean? I include and inheritance QObject in the classes... Can you explain (with an example?)?

@marcel:

2) How can I read the version? When I do this:

setData("File generated by QQMsn " + VERSION);

setData("File generated by QQMsn " + VERSION);

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(debugger.cpp)

It doesn't work (VERSION not declared). How can I read it? Can you give a little example?

3) Which thing do I still have to delete in main? Do you mean this:

debugger *debug = new debugger("QQMsn_debug",true);
cmsn *msn = new cmsn();
Window_Login *window_login = 0;
Window_Login_Busy *login_busy = 0;

debugger *debug = new debugger("QQMsn_debug",true);
cmsn *msn = new cmsn();
Window_Login *window_login = 0;
Window_Login_Busy *login_busy = 0;

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?

But when I put these in main, I can't use extern in other files... Can you give an example?

[wysota]

@wysota:

1) What do you mean? I include and inheritance QObject in the classes... Can you explain (with an example?)?

From what I understand you have a declaration like the following somewhere:

extern SomeClass obj;

extern SomeClass obj;

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where SomeClass inherits QObject. So I suggest to use a pointer to the object instead of the object itself, so that you can create the object and assign it to the pointer after the application object is created.

[Voldemort]

From what I understand you have a declaration like the following somewhere:

extern SomeClass obj;

extern SomeClass obj;

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where SomeClass inherits QObject. So I suggest to use a pointer to the object instead of the object itself, so that you can create the object and assign it to the pointer after the application object is created.

I understand a bit what you meaning, but not everything. Can you give an example?

[marcel]

Have you thought about applying the singleton pattern?
This means that your static objects will have something like a static GetInstance method that will return a pointer to the single instance (static,also ).

There will be no need to use "extern", just call GetInstance wherever you need it ( but make sure to include the necessary files ).

Regards

[wysota]

I second what Marcel says. I'd even suggest subclassing QApplication and putting your object as a member of the application.

class MyApp : public QApplication{
public:
  MyApp(int a, char **b) : QApplication(a,b){
    m_x = new X(this);
  }
  X *x() const { return m_x; }
private:
  X *m_x;
};

class MyApp : public QApplication{
public:
  MyApp(int a, char **b) : QApplication(a,b){
    m_x = new X(this);
  }
  X *x() const { return m_x; }
private:
  X *m_x;
};

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A redefinition of qApp might also come in handy:

#ifdef qApp
#undef qApp
#endif
#define qApp static_cast<MyApp*>(QCoreApplication::instance())

#ifdef qApp
#undef qApp
#endif
#define qApp static_cast<MyApp*>(QCoreApplication::instance())

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[marcel]

I second what Marcel says. I'd even suggest subclassing QApplication and putting your object as a member of the application.

class MyApp : public QApplication{
public:
  MyApp(int a, char **b) : QApplication(a,b){
    m_x = new X(this);
  }
  X *x() const { return m_x; }
private:
  X *m_x;
};

class MyApp : public QApplication{
public:
  MyApp(int a, char **b) : QApplication(a,b){
    m_x = new X(this);
  }
  X *x() const { return m_x; }
private:
  X *m_x;
};

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A redefinition of qApp might also come in handy:

#ifdef qApp
#undef qApp
#endif
#define qApp static_cast<MyApp*>(QCoreApplication::instance())

#ifdef qApp
#undef qApp
#endif
#define qApp static_cast<MyApp*>(QCoreApplication::instance())

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Yes. Now he won't even need to include additional files because there will be qApp.

Regards

[Voldemort]

I understand what you mean. But I have questions:

#ifdef qApp
#undef qApp
#endif
#define qApp static_cast<MyApp*>(QCoreApplication::instance())

#ifdef qApp
#undef qApp
#endif
#define qApp static_cast<MyApp*>(QCoreApplication::instance())

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1) Where do I have to put this part? Every file? Just in the class file? Somewhere else?

2) With that code I have to include some classes I use (the part above my main function in main.cpp)?

3) Do I have to instantiate the class in all files or just in the main function? Or does it work in another way?

4) Can I put the delete lines (now at the bottom of my main function in main.cpp) in the destructor of the class?

[marcel]

1. In the source file in which you will implement your subclass of QApplication.
2. Only your QApplication class.
3. Just the main function.
4. Yes, if they will be the members of your custom QApplication, then you can put them in its destructor.

Regards

[wysota]

1. In the source file in which you will implement your subclass of QApplication.

Header file, to be exact.

[Voldemort]

I've tried to make such a class (source is in the attachment), but I get these errors:

/home/quinten/QQMsn_test/src/QQMsnApplication.h: In constructor ‘QQMsnApplication::QQMsnApplication(int, char**)’:
/home/quinten/QQMsn_test/src/QQMsnApplication.h:31: error: expected `{' at end of input
/home/quinten/QQMsn_test/src/main.cpp: In function ‘int main(int, char**)’:
/home/quinten/QQMsn_test/src/main.cpp:35: error: ‘arg’ was not declared in this scope
/home/quinten/QQMsn_test/src/main.cpp:37: error: invalid use of member (did you forget the ‘&’ ?)
/home/quinten/QQMsn_test/src/main.cpp:37: error: base operand of ‘->’ is not a pointer
/home/quinten/QQMsn_test/src/main.cpp:38: error: invalid use of member (did you forget the ‘&’ ?)
/home/quinten/QQMsn_test/src/main.cpp:38: error: base operand of ‘->’ is not a pointer
make[2]: *** [CMakeFiles/QQMsn.dir/src/main.o] Fout 1
make[1]: *** [CMakeFiles/QQMsn.dir/all] Fout 2
make: *** [all] Fout 2

Why? What do I wrong?

[wysota]

In header file this:

QQMsnApplication(int a, char **b) : QApplication(a,b);

QQMsnApplication(int a, char **b) : QApplication(a,b);

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should be like this:

QQMsnApplication(int a, char **b);

QQMsnApplication(int a, char **b);

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[Voldemort]

That solves some errors, but these are still present:

/home/quinten/QQMsn_test/src/main.cpp: In function ‘int main(int, char**)’:
/home/quinten/QQMsn_test/src/main.cpp:35: error: ‘arg’ was not declared in this scope
/home/quinten/QQMsn_test/src/main.cpp:37: error: ‘window_login’ was not declared in this scope
make[2]: *** [CMakeFiles/QQMsn.dir/src/main.o] Fout 1
make[1]: *** [CMakeFiles/QQMsn.dir/all] Fout 2
make: *** [all] Fout 2

What is the bug?

[wysota]

"‘arg’ was not declared in this scope" - should probably be "argc" or "argv".

[marcel]

You have to use the members from QMSNApplication, namely:

m_window_login = new Window_Login();
    m_login_busy = new Window_Login_Busy();

m_window_login = new Window_Login();
    m_login_busy = new Window_Login_Busy();

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I didn't look too much at the code, but if you don't have accessors for them, then create them.

As for the "arg" error, make sure that the parameter names of main coincide with the parameters of your qmsnapplication - argc and argv.

Regards