Beginner problem with connect

[lucastonon]

That line you asked me is the way I found at the internet to get a 'handle' to an object created by Qt Designer, instead of manually creating it with commands. It works fine in program.cpp but not in window1.cpp.
Thanks.

[Santosh Reddy]

Looks like you still have to figure out the basic object creation and scope work (it's C++ stuff)

//program.cpp
wnd1 w1; //this will create object on stack and will be destroyed as soon as function returns
w1.Initialize(); //this is ok

//program.cpp
wnd1 w1; //this will create object on stack and will be destroyed as soon as function returns
w1.Initialize(); //this is ok

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//window1.cpp
program oProg; //this not good, you are creating a global QMainWindow, that means you are trying to create a widget even before QApplication is created
 
void wnd1::Initialize() {
  QPushButton *b = oProg.centralWidget()->findChild<QPushButton *>("button1"); // you are not supposed to get the member widgets of other class this way, it will work but will end up in problems later
  wnd1 w1;  //this will create object on stack and will be destroyed as soon as function returns
  w1.connect(b, SIGNAL(clicked()), SLOT(test())); //there is no such version of connect function, hence the error, and moreover it does not make sense to connect a object which will be deleted before this function returns. So even if you were able to get the correct version of the function, your slot will never get called, as the object itself is destroyed before this function returns
}

//window1.cpp
program oProg; //this not good, you are creating a global QMainWindow, that means you are trying to create a widget even before QApplication is created

void wnd1::Initialize() {
  QPushButton *b = oProg.centralWidget()->findChild<QPushButton *>("button1"); // you are not supposed to get the member widgets of other class this way, it will work but will end up in problems later
  wnd1 w1;  //this will create object on stack and will be destroyed as soon as function returns
  w1.connect(b, SIGNAL(clicked()), SLOT(test())); //there is no such version of connect function, hence the error, and moreover it does not make sense to connect a object which will be deleted before this function returns. So even if you were able to get the correct version of the function, your slot will never get called, as the object itself is destroyed before this function returns
}

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Please try, as I suggested in my earlier post

[lucastonon]

Mmm I got it, but I wanted to do that (connecting) in another .cpp file, just because of organization, can't it be done?

Another question using your example:

//program.cpp
program::program(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::program)
{
    ui->setupUi(this);
 
    wnd1 *w1 = new wnd1;
    connect(ui->button1, SIGNAL(clicked()), w1, SLOT(test()));
 
}
 
//window1.cpp
void wnd1::test() { //is it ok doing that in this function?[/COLOR]
  program *ep = new program;
  QMessageBox::information(ep, "a", "b");
  delete ep;
}

//program.cpp
program::program(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::program)
{
    ui->setupUi(this);

    wnd1 *w1 = new wnd1;
    connect(ui->button1, SIGNAL(clicked()), w1, SLOT(test()));

}

//window1.cpp
void wnd1::test() { //is it ok doing that in this function?[/COLOR]
  program *ep = new program;
  QMessageBox::information(ep, "a", "b");
  delete ep;
}

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Thanks

[Santosh Reddy]

it can be done, (and is done most of times this way), you can create a signal of program class (instead of button signal) and connect to win1 class objects

[lucastonon]

You mean creating a signal for something like a tab? How to do that? :s
Thanks

[Santosh Reddy]

here is an example

//program.h
#include <QtGui>
#include "ui_program.h"
class wnd1;
class program : public QMainWindow, public 
{
	Q_OBJECT;
public:
	explicit program(QWidget * parent = 0);
signals:
	void openButtonClicked(void);
private:
	Ui::program * ui;
	wnd1 * w1;
};
 
//program.cpp
#include "program.h"
#include "window1.h"
 
program::program(QWidget *parent) : 
    QMainWindow(parent),
    ui(new Ui::program()),
	w1(new wnd1(this))
{
    ui->setupUi(this);
	connect(this, SIGNAL(openButtonClicked()), w1, SLOT(test()));
}
 
program::~program()
{
    delete ui;
}
 
//window1.h
#include <QtGui>
class wnd1 : public QObject
{
	Q_OBJECT;
public:
	explicit wnd1(QObject * parent = 0);
public slots:
	void test(void);
};
 
//window1.cpp
#include "window1.h"
wnd1::wnd1(QObject * parent) : QObject(parent)
{
	;
}
 
void wnd1::test(void)
{
	;//do something
}

//program.h
#include <QtGui>
#include "ui_program.h"
class wnd1;
class program : public QMainWindow, public 
{
	Q_OBJECT;
public:
	explicit program(QWidget * parent = 0);
signals:
	void openButtonClicked(void);
private:
	Ui::program * ui;
	wnd1 * w1;
};

//program.cpp
#include "program.h"
#include "window1.h"

program::program(QWidget *parent) : 
    QMainWindow(parent),
    ui(new Ui::program()),
	w1(new wnd1(this))
{
    ui->setupUi(this);
	connect(this, SIGNAL(openButtonClicked()), w1, SLOT(test()));
}

program::~program()
{
    delete ui;
}

//window1.h
#include <QtGui>
class wnd1 : public QObject
{
	Q_OBJECT;
public:
	explicit wnd1(QObject * parent = 0);
public slots:
	void test(void);
};

//window1.cpp
#include "window1.h"
wnd1::wnd1(QObject * parent) : QObject(parent)
{
	;
}

void wnd1::test(void)
{
	;//do something
}

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[lucastonon]

it can be done, (and is done most of times this way), you can create a signal of program class (instead of button signal) and connect to win1 class objects

I don't think you got. What I understood from this quoted post was that if I had a tab widget, I could connect example: tab1 to wnd1(window1.cpp), tab2 to wnd2(window2.cpp); and then every control from the connected tab would signal the connected object, but forget that. I just wanted to do something like:

//program.cpp
program::program(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::program)
{
    ui->setupUi(this);
 
    wnd1 w1;
    w1.Initialize();
 
}
 
//window1.cpp
void wnd1::Initialize() { 
connect(ui->button1, SIGNAL(clicked()), this, SLOT(test1()));
connect(ui->button2, SIGNAL(clicked()), this, SLOT(tes2t()));
connect(ui->button3, SIGNAL(clicked()), this, SLOT(test3()));
connect(ui->button4, SIGNAL(clicked()), this, SLOT(test4()));
connect(ui->button5, SIGNAL(clicked()), this, SLOT(test5()));
// but i don't know how to get a handle the buttons in window1.cpp since 'ui' is from program.cpp
}

//program.cpp
program::program(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::program)
{
    ui->setupUi(this);

    wnd1 w1;
    w1.Initialize();

}

//window1.cpp
void wnd1::Initialize() { 
connect(ui->button1, SIGNAL(clicked()), this, SLOT(test1()));
connect(ui->button2, SIGNAL(clicked()), this, SLOT(tes2t()));
connect(ui->button3, SIGNAL(clicked()), this, SLOT(test3()));
connect(ui->button4, SIGNAL(clicked()), this, SLOT(test4()));
connect(ui->button5, SIGNAL(clicked()), this, SLOT(test5()));
// but i don't know how to get a handle the buttons in window1.cpp since 'ui' is from program.cpp
}

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Sorry for the misunderstanding.

[Santosh Reddy]

// but i don't know how to get a handle the buttons in window1.cpp since 'ui' is from program.cpp

I was trying to tell you that, make the connections in program.cpp not is window1.cpp, move the connect statements to program class ctor (this is a standard way doing).
In program.cpp you will have handles to buttons, and you also know that wnd1 class has an public slot testx()

[lucastonon]

Ok I'll make the connections at program.cpp. But in case in window1.cpp I need to get the text of a text edit I would need to have ui->textEdit1 in window1.cpp, but I can only use that in program.cpp

[Santosh Reddy]

You are still getting it worng, do not create wnd1 variable in program.cpp constructor. (it will not work) also, refer to my post (Post #4) for example to create objects

I can see you are complicating your situation, Please review your code again.

Problem: You are tyring to create a object of program class with in a slot connected to a signal emitted by program class it self, why do you need to do it this wa? I am not sure of your requrements, but you don't want this.

Either create program class object in wnd1 class or create wnd1 class object in program class, but don't do both