Multi Dimensional Array

mda.rb

class MultiDimensionalArray
  def self.[](*dimension_sizes)
    new(*dimension_sizes)
  end

  def self.cube(dimensions, dimension_size)
    new(*Array.new(dimensions, dimension_size))
  end

  def initialize(*dimension_sizes)
    @dims = dimension_sizes.dup.freeze
    @data = Hash.new 0 # with default value
  end

  def [](*idx)
    index_check(idx)
    @data[idx]
  end

  def []=(*idx, val)
    index_check(idx)
    @data[idx] = val
  end

  def default
    @data.default
  end

  def default=(val)
    @data.default = val
  end

private
  def index_check(idxs)
    raise ArgumentError, "Wrong number of dimensions: %p" % [idxs] unless idxs.size == @dims.size

    @dims.zip idxs do |d,i|
      raise ArgumentError, "Wrong index: %p" % i unless 0 <= i && i < d
    end
  end
end


mda = MultiDimensionalArray[10, 20]
p mda[1,2]
p mda[5,4]=6
mda[5] rescue nil
p mda[5,4]