subtract method

DayDart subtract(
  1. int num, [
  2. DayUnits unit = DayUnits.D
])

返回DayDart对象，并减去指定的时间。

Implementation

DayDart subtract(int num, [DayUnits unit = DayUnits.D]) {
  switch (unit) {
    case DayUnits.y:
      year($y - num);
      break;
    case DayUnits.M:
      month($M - num);
      break;
    case DayUnits.D:
      day($D - num);
      break;
    case DayUnits.h:
      hour($h - num);
      break;
    case DayUnits.m:
      minute($m - num);
      break;
    case DayUnits.s:
      second($s - num);
      break;
    case DayUnits.ms:
      millisecond($ms - num);
      break;
  }
  return clone();
}