Polymorphism didn't work

[VRonin]

@Zunneh No, you just add the override keyword in the base class to tell the compiler to make 100% sure you are indeed reimplementing a virtual method. It's just a safety feature, no change in code behaviour

[Zunneh]

@VRonin yeah but where i should create the object ? the green ball , you tell me i can't create it in the base class because it will only use base class methods

[VRonin]

members can be created anywhere you want, the base class is fine, what I meant is that if you create Personnage a; it will behave as a Personnage. Always.

[Zunneh]

Personnage.h

 ifndef PERSONNAGE_H
 #define PERSONNAGE_H
 #include <QMainWindow>
 #include <QtWidgets>

 class Personnage:public QWidget
{
public: 

Personnage(QWidget *parent=0);
~Personnage();
virtual void moveToUp();
virtual void moveToLeft();
virtual void moveToRight();
virtual void moveToDown();

protected:

  int m_x;
  int m_y;
  QLabel *test;
 };

void moveUp(Personnage *e);
void moveLeft(Personnage *e);
void moveRight(Personnage *e);
void moveDown(Personnage *e);

 #endif // PERSONNAGE_H

Personnage.cpp

 #include "personnage.h"

 Personnage::Personnage(QWidget *parent):QWidget(parent)
{

QLabel *test=new QLabel(this);
test->setFixedSize(30,30);
QPixmap image5("/Users/mac/Documents/Qt projet/PolymorphysmeV1/bouton-vert.png");
test->setPixmap(image5);

}

void Personnage::moveToUp()
{

move(40,m_y);

}

void Personnage::moveToLeft()

{

move(20,m_y);

}

void Personnage::moveToRight()

{

move(0,m_y);

}

void Personnage::moveToDown()

{

move(30,m_y);

}

void moveUp(Personnage *e)

{

e->moveToUp();

}

void moveLeft(Personnage *e)

{

 e->moveToLeft();

}

void moveRight(Personnage *e)

{

e->moveToRight();

}

void moveDown(Personnage *e)

{

e->moveToDown();

}

Now this is the child Flash.h

#ifndef FLASH_H
#define FLASH_H
#include"personnage.h"
class Flash:public Personnage

{

public:
void moveToUp() override;
void moveToLeft() override;
void moveToRight() override;
void moveToDown() override;

private:

 };

#endif // FLASH_H

This is the child flash.cpp

#include "flash.h"
void Flash::moveToUp()
{
move(10,10);
}
void Flash::moveToLeft()
{
move(m_x+10,m_y);
}
void Flash::moveToRight()
{
move(m_x-10,m_y);
}
void Flash::moveToDown()
{
move(m_x,m_y+10);
}

now in main program MainWindow.cpp

lawl=new Personnage(this);
flash =new Flash; 
moveUp(lawl); //This work
moveUp(flash); // this don't work its like i didn't write this command

[VRonin]

@Zunneh said in Polymorphism didn't work:

moveUp(flash); // this don't work its like i didn't write this command

lawl and flash are 2 different items. Since you never give a parent to flash it remains as a separate top level window and since you never call show on it it is never displayed on screen. move works as expected

[Zunneh]

@VRonin Flash is the same object created with lawl (Personnage ) how can i do it ?

[J.Hilk]

@Zunneh

flash =new Flash(this);
auto pers = qobject_cast<Personage*>(flash);
if(pers)
    pers->moveUp();
flash->moveUp();

---

really, you should consider an other approach:

class myDot :  public QLabel
{
 enum MoveSpeed{
     Personage = 1,
     Tortue = 2,
     Flash  = 10
}; E_ENUM(MoveSpeed)
.....

public: 
void moveToUp(MoveSpeed speed){
     move (m_x, m_y - static_cast<int>(speed));
}

}

[VRonin]

@Zunneh said in Polymorphism didn't work:

Flash is the same object created with lawl

It is not. 2 new = 2 different objects

[Zunneh]

@VRonin yeah you are right i tried it and its 2 different objects , so i forget something , i'm moving 2 Different objects and my goal is to move one object with different form

[VRonin]

my goal is to move one object with different form

@SGaist said in Polymorphism didn't work:

Technically you don't need three subclasses, you can just have setters which set the speed of your "Personnage" class.

@J.Hilk said in Polymorphism didn't work:

really, you should consider an other approach:

class myDot :  public QLabel
{
 enum MoveSpeed{
     Personage = 1,
     Tortue = 2,
     Flash  = 10
}; E_ENUM(MoveSpeed)
.....

public: 
void moveToUp(MoveSpeed speed){
     move (m_x, m_y - static_cast<int>(speed));
}

}

[Zunneh]

thank you guys , it work :)