Launch School challenge: Circular Buffer

circular_buffer.rb

class CircularBuffer
  class BufferEmptyException < RuntimeError; end
  class BufferFullException < RuntimeError; end

  def initialize(size)
    @size = size
    @buffer = Array.new
  end

  def write(value)
    return if value.nil?
    @buffer.push(value) unless exception_on_full
  end

  def write!(value)
    return if value.nil?
    @buffer.shift if full?
    write(value)
  end

  def read
    @buffer.shift unless exception_on_empty
  end

  def clear
    @buffer.clear
  end

  private

  def full?
    @buffer.size >= @size
  end

  def exception_on_full
    raise BufferFullException.new if full?
  end

  def empty?
    @buffer.size == 0
  end

  def exception_on_empty
    raise BufferEmptyException.new if empty?
  end
end

Original challenge at https://launchschool.com/gists/0164b2eb