trouble linking to public slot

[jiggersplat]

I am having trouble calling a slot directly from subclass of QListWidget. It fails to link claiming an undefined reference to MyClass::MySlot. If instead of calling it, I just connect to slot and emit the appropriate signal everything works fine. It seems to me that it's probably a compiler/qmake/makefile issue but I'm not sure. Below is a rough approximation of the issue I'm having. I have omitted all the #include for the sake of brevity.

I have a subclass of QObject that looks roughly like

class MyClass : public QObject {
 
Q_OBJECT
 
public:
    MyClass(QObject* parent = NULL) : QObject(parent) { }
    void MyFunc() { 
        // do some work
    }
 
public slots:
   void MySlot() {
       // do some work
   }
}

class MyClass : public QObject {

Q_OBJECT

public:
    MyClass(QObject* parent = NULL) : QObject(parent) { }
    void MyFunc() { 
        // do some work
    }

public slots:
   void MySlot() {
       // do some work
   }
}

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And...

class MyListWidget : public QListWidget {
 
Q_OBJECT
 
private:
    MyClass* foo;
 
public:
    MyListWidget(QWidget* parent = NULL) : QListWidget(parent) { }
 
public slots:
    void bar() {
       // won't compile, linker fails - undefined reference to 'MyClass::MySlot'
       foo->MySlot();
    }
 
    void baz() {
        // this compiles and works fine
        QObject::connect(this, SIGNAL(callSlot), foo, SLOT(MySlot()));
        emit callSlot();
        QObject::disconnect(this, SIGNAL(callSlot), foo, SLOT(MySlot()));
 
       // also works
       foo->MyFunc();
    }
 
signals:
    void callSlot();
}

class MyListWidget : public QListWidget {

Q_OBJECT

private:
    MyClass* foo;

public:
    MyListWidget(QWidget* parent = NULL) : QListWidget(parent) { }

public slots:
    void bar() {
       // won't compile, linker fails - undefined reference to 'MyClass::MySlot'
       foo->MySlot();
    }

    void baz() {
        // this compiles and works fine
        QObject::connect(this, SIGNAL(callSlot), foo, SLOT(MySlot()));
        emit callSlot();
        QObject::disconnect(this, SIGNAL(callSlot), foo, SLOT(MySlot()));

       // also works
       foo->MyFunc();
    }

signals:
    void callSlot();
}

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[mentalmushroom]

could you provide a more complete sample. it is not clear what you include and where.

[jiggersplat]

MyListWidget does in fact include the header for MyClass if that's what you were getting at. Besides, it's a linker problem, not a compiler problem so I don't think #includes are the issue. I can provide more detail if you still think it will help.

[mentalmushroom]

check out this code. it compiles fine and gives linker error. and of course, there is an error in the code

#include <QtCore>
 
class A
{
public:
	void testMethod();
};
 
int main(int argc, char *argv[])
{
	QCoreApplication app(argc, argv);
 
	A a;
	a.testMethod();
 
	return app.exec();
}

#include <QtCore>

class A
{
public:
	void testMethod();
};

int main(int argc, char *argv[])
{
	QCoreApplication app(argc, argv);
	
	A a;
	a.testMethod();

	return app.exec();
}

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[jiggersplat]

I'm not sure I understand what point you are making. Your example won't link because you have not written the implementation of testMethod() anywhere, correct? The function that refuses won't link in mine has a body so that's not the problem. I can even run the function in question using signals, I just won't link when I try and call it directly.

---

Added after 10 minutes:

fixed it. problem with the .pro file.