RandomBag

A RandomBag ensures that per interval [fillings * itemCount], every different item in it will be given back [fillings] times. Once the bag is empty, it is automatically refilled, either from a fixed array or by calling a delegate.

An example for that is used in some implementations of Tetris. The bag is filled with one instance (fillings=1) of each of the seven different pieces. Every time the next piece is needed, a random one is taken out of the bag until the bag is empty. That way, any two pieces are never longer than 14 pulls apart - and even that is only the case if the first and the last piece in the bag are the same one.

Example

{C#}
public class RandomBagExample : MonoBehaviour
{
    private enum TetrisPiece
    {
        Line, Square, T, J, L, S, Z
    }

    RandomBag<TetrisPiece> pieceBag;

    void Awake()
    {
        // Get an array with each value of TetrisPiece
        TetrisPiece[] tetrisPieceArray = (TetrisPiece[]) Enum.GetValues(typeof (TetrisPiece));

        // Create the bag containing two instances of every value of TetrisPiece
        pieceBag = new RandomBag<TetrisPiece>(tetrisPieceArray, 2);

        // Gets 50 items from the bag. The bag will be filled with 14 TetrisPieces and
        // automatically refilled with 14 more when needed. No two pieces will ever be
        // more than 14 calls apart - and even that will only happen if that piece was
        // the first and last item in the current 14 piece bag filling.
        StringBuilder str = new StringBuilder();
        for (var i = 0; i < 50; i++)
        {
            str.Append(pieceBag.PopRandomItem());
            str.Append(", ");
        }

        Debug.Log(str);

        // Example output:
        // T, Z, J, Square, Z, S, L, L, S, Line, J, Line, Square, T, Square, Z,
        // S, T, Line, Square, Z, T, J, Line, S, L, J, L, S, Z, Line, J, Line,
        // J, L, L, S, T, T, Z, Square, Square, Z, T, S, Z, J, J, L, Line, 
    }
}

Dependencies

• LINQExtensions