Declare and Initialize a const Struct in Class Header

Question

I am looking for way to Declare and Initialize a constant struct in my Class Header file. The class is being used by an MFC app, as you can see. The layers on my MFC Dialog will never change, so I would like to delcare them constantly.

I am looking for something like this:

class CLayerDialog : CDialogEx
{
...
public:
   const LAYER_AREA(CPoint(0, 70), CPoint(280, 140));
}

The struct:

struct LAYER_AREA{
   CPoint topLeft;
   CPoint bottomRight;
};

What is the best way to do this, to save as much performance as possible and to easily maintain the layers?

Answer 1

Do you mean a static const member variable?

// header file
class CLayerDialog : CDialogEx
{
/* ... */
public:
   static const LAYER_AREA myvar;
};

// source file
const LAYER_AREA CLayerDialog::myvar(CPoint(0, 70), CPoint(280, 140));

Note that the variable must be defined out-of-line (in the source file rather than the header file). You'll also need an appropriate constructor for struct LAYER_AREA as well.

Answer 2

You can do something like this: ( I have made a few assumptions about the classes you had not provided )

in header file

class CDialogEx
{
   public:
      CDialogEx (){}
};

class CPoint
{
   public:
      CPoint ( const int& _x, const int& _y ):x(_x), y(_y){}

   private:
      int x;
      int y;

};

struct LAYER_AREA
{
   CPoint topLeft;
   CPoint bottomRight;
   LAYER_AREA ( CPoint tl, CPoint br ):
      topLeft ( tl ), bottomRight ( br )
   {
   }
};

class CLayerDialog : CDialogEx
{
   public:
      CLayerDialog ();
      const LAYER_AREA myStructVar;
};

in .cpp file

CLayerDialog::CLayerDialog()
  : myStructVar ( CPoint(0, 70), CPoint(280, 140) )
{

}