ReqLen constructor Null safety

  1. int len,
  2. {String? blank,
  3. String? diff}

Constrains the length (number of items).

len the length or number of items; it must be >= 0. blank the error message in case of a null or empty input value. diff the error message if the length is different from len.


ReqLen(int len, {String? blank, String? diff})
    : _reqLenVal = Pair(Req(blank: blank), Len(len, diff: diff));