export default function DragEvent(type, {
  sourceEvent,
  subject,
  target,
  identifier,
  active,
  x, y, dx, dy,
  dispatch
}) {
  Object.defineProperties(this, {
    type: {value: type, enumerable: true, configurable: true},
    sourceEvent: {value: sourceEvent, enumerable: true, configurable: true},
    subject: {value: subject, enumerable: true, configurable: true},
    target: {value: target, enumerable: true, configurable: true},
    identifier: {value: identifier, enumerable: true, configurable: true},
    active: {value: active, enumerable: true, configurable: true},
    x: {value: x, enumerable: true, configurable: true},
    y: {value: y, enumerable: true, configurable: true},
    dx: {value: dx, enumerable: true, configurable: true},
    dy: {value: dy, enumerable: true, configurable: true},
    _: {value: dispatch}
  });
}

DragEvent.prototype.on = function() {
  var value = this._.on.apply(this._, arguments);
  return value === this._ ? this : value;
};