Qt header files suggestion

[chandan]

Thanks for your help. Will this forward declaration will increase the time efficiency? I mean, currently I am writing an application which contains lots of customised widgets and dialogs and whenever I am changing any of their header files then the application takes 3-4 minutes to build. So if I use the forward declaration then will it decrease the build time?

Chandan

[Lykurg]

Simple example:
You have two header files a.h and b.h. b.h looks like

#ifndef _B_H
#define _B_H
#include "a.h"
class B
{
  A* a;
};
#endif

#ifndef _B_H
#define _B_H
#include "a.h"
class B
{
  A* a;
};
#endif

To copy to clipboard, switch view to plain text mode 

So if you change something in a.h not only this needs to be recompiled, but also b.h. Otherwise (if you use forward declaration) only a.h needs to be recompiled. So yes, you can speed up compilation time.

#ifndef _B_H
#define _B_H
class A;
class B
{
  A* a;
};
#endif

#ifndef _B_H
#define _B_H
class A;
class B
{
  A* a;
};
#endif

To copy to clipboard, switch view to plain text mode 

Also, the compiler has not to include the header file here, which also saves some time, but that is not much...