"Cannot" move pointer - c++

Question

In my code I have:
template<class Ui_Dialog>
QDialog* Base_Dialog<Ui_Dialog>::set_caller(QDialog *new_caller)
{
QDialog* old_caller = caller_;
caller_ = new_caller;//Here I'm trying to set this to new caller
return old_caller;
}
but after setting the caller to new caller and exiting from this fnc, when I call caller I'm still getting the old caller instead of new one, as if no changes were made. Why?
EDIT:
//caller is defined in a following way:
class Main_Dialog : public Base_Dialog<Ui::Main_Dialog> {};
EDIT 2:
The interesting thing is that if instead of public Base_Dialog I alter Base_Dialog to non-template and define Main_Dialog as:
class Main_Dialog : public Base_Dialog, private Ui::Main_Dialog {};
Then it works as intended. Why?!
EDIT 3:
class Main_Dialog;
template<class Ui_Dialog>
class Base_Dialog : public QDialog, protected Ui_Dialog
{
// Q_OBJECT //no signals/slots
protected:
Main_Dialog* main_dlg_;
QDialog* caller_;
public:
Base_Dialog(Main_Dialog *main_dlg, QDialog *caller, QWidget *parent = nullptr);
QDialog* set_caller(QDialog *);
QDialog* clear_caller();
Main_Dialog* clear_main_dlg();
};
/*----------------*/
#include "Main_Dialog.hpp"
template<class Ui_Dialog>
Base_Dialog<Ui_Dialog>::Base_Dialog(Main_Dialog *main_dlg,QDialog *caller, QWidget *parent):
QDialog(parent),
main_dlg_(main_dlg),
caller_(caller)
{
//setupUi(this);
}
#include <QtDebug>
template<class Ui_Dialog>
QDialog* Base_Dialog<Ui_Dialog>::set_caller(QDialog *new_caller)
{
QDialog* old_caller = caller_;
caller_ = new_caller;
return old_caller;
}
#include "_1Dialog.hpp"
#include "_2Dialog.hpp"
class Main_Dialog : public Base_Dialog<Ui::Main_Dialog>
{
Q_OBJECT
QSet<QDialog*>* dialogs_;
private:
template<class Dialog,class Caller>
bool already_created_(Caller*&, QDialog*& already_exists)const;
template<class Dialog,class Caller, class Parent>
QDialog* create_(Caller*,Parent*);
/*template<class Dialog>
void show_();*/
/* template<class Dialog,class Caller>
QDialog* find_(Caller*)const;*/
public:
explicit Main_Dialog(QWidget *parent = 0);
template<class Dialog,class Caller>
QDialog* get_dialog(Caller*& caller);
public slots:
void _1clicked();
void _2clicked();
};
template<class Dialog,class Caller>
bool Main_Dialog::already_created_(Caller*& caller,QDialog*& already_exists)const
{/*the already_exists is introduced here in order to remove repetions of code and
searching*/
auto beg = dialogs_->begin();
auto end = dialogs_->end();
while(beg != end)
{
if(dynamic_cast<Dialog*>(*beg))
{
already_exists = *beg;
static_cast<Base_Dialog*>(already_exists)->set_caller(caller);
return true;
}
++beg;
}
return false;
}
template<class Dialog,class Caller, class Parent>
QDialog* Main_Dialog::create_(Caller *caller, Parent *parent)
{
return (*dialogs_->insert(new Dialog(this,caller,parent)));
}
template<class Dialog,class Caller>
QDialog* Main_Dialog::get_dialog(Caller *&caller)
{
QDialog* already_exists = nullptr;
if (already_created_<Dialog>(caller,already_exists))
{
return already_exists;
}
else
{
return create_<Dialog>(caller,this);
}
#include "Base_Dialog.hpp"
#include "ui__1Dialog.h"
class Main_Dialog;
class _1Dialog : public Base_Dialog<Ui::_1Dialog>
{
Q_OBJECT
public:
explicit _1Dialog(Main_Dialog* main_dlg, QDialog*caller, QWidget *parent = 0);
private slots:
void _2clicked();
void caller_clicked();
void main_clicked();
};
#endif // _1DIALOG_HPP
#include "_1Dialog.hpp"
#include "_2Dialog.hpp"
#include "Main_Dialog.hpp"
_1Dialog::_1Dialog(Main_Dialog* main_dlg, QDialog*caller, QWidget *parent) :
Base_Dialog(main_dlg,caller,parent)
{
setupUi(this);
}
void _1Dialog::_2clicked()
{
this->hide();
main_dlg_->get_dialog<_2Dialog>(this)->show();
}
void _1Dialog::caller_clicked()
{
this->hide();
caller_->show();
}
void _1Dialog::main_clicked()
{
this->hide();
main_dlg_->show();
}
}
#endif // MAIN_DIALOG_HPP

Answer 1

I think your problem not in set_caller. Next works for me:
#include <iostream>
using namespace std;
class QDialog {
int i;
public:
QDialog() : i(0) {}
QDialog(int i) : i(i) {}
void me() { cout << i << endl; }
};
namespace UI {
class Main_Dialog {}; // EDITED
}
template<class Ui_Dialog>
class Base_Dialog : public QDialog, protected Ui_Dialog
{
QDialog* caller_;
public:
QDialog* set_caller(QDialog *new_caller);
QDialog* get_caller() {return caller_; } ;
};
template<class Ui_Dialog>
QDialog* Base_Dialog< Ui_Dialog>::set_caller(QDialog *new_caller)
{
QDialog* old_caller = caller_;
caller_ = new_caller;//Here I'm trying to set this to new caller
return old_caller;
}
class Main_Dialog : public Base_Dialog<UI::Main_Dialog> {
public:
};
int main()
{
QDialog q1(1);
QDialog q2(2);
Main_Dialog md;
md.set_caller(&q1);
md.get_caller()->me();
md.set_caller(&q2);
md.get_caller()->me();
return 0;
}