Digit.len constructor
Constrains the input data to the digits 0-9
and its length (number of
digits) to len
digits.
len
the number of digits; it must be > 0.
mal
"malformed", the error message if non-digit characters are found;
the default value is 'non-digit character(s) found'.
diff
the error message if the number of digits is different from len
.
Implementation
Digit.len(int len, {String? mal, String? diff})
: assert(len > 0),
_valDig = _DigitImpl(mal, Len(len, diff: diff).call).call;