How to initialize a private static const array of a private child class in a class?

I've been working on my homework project and now I am to declare a class:

Code:

---

#define PIECE_SIZE 5
#define PIECE_NUM 2
#include <vector>
class Piece
{
        class InternalPiece
        {
                std::vector<bool> Array;
               
                public:
                InternalPiece(const bool a[])
                {
                        for (int i = 0; i < PIECE_SIZE * PIECE_SIZE; ++i)
                                Array[i] = a[i];
                }
                bool operator()(const int &x, const int &y) const
                {
                        return (bool)Array[x * PIECE_SIZE + y];
                }
        };
        public:
        static const InternalPiece pieces[];

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And now how am I to initialize the array `pieces'? Initialize it within the class definition is unavailable:

Code:

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error: expected constructor, destructor, or type conversion before ‘=’ token

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And so is to initialize when you have a Piece object, since the class InternalPiece is private:

Code:

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error: ‘class Piece::InternalPiece’ is private

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Anyone knows how to solve this? Great thanks.

Code:

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//declaration
static const InternalPiece pieces[];


//definition in global scope
const Piece::InternalPiece Piece::pieces[N] = {true, true};

---

This doesn't work since:

1. InternalPiece variables are constructed from a bool array.
2. The class InternalPiece is private hence we cannot call the constructor outside the class Piece definition.

Quote:

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Originally Posted by jinhao

Code:

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//declaration
static const InternalPiece pieces[];


//definition in global scope
const Piece::InternalPiece Piece::pieces[N] = {true, true};

---

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Since InternalPiece is private, why is it being exposed to the public via the pieces member variable? This consideration aside, I can suggest that you provide a default constructor, and then write in a source file:

Code:

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const Piece::InternalPiece Piece::pieces[PIECE_NUM];

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Incidentally, change PIECE_SIZE and PIECE_NUM from macros to static const integer member variables of Piece, or possibly an enum in Piece.

Quote:

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Originally Posted by ryanli

# The class InternalPiece is private hence we cannot call the constructor outside the class Piece definition.

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That is true, but by correctly qualifying the static member's name, one can initialise it outside of the definition of the class.