prefer-number-format

added in: 1.6.0

warning

⚙️🛠

Warns when int, num or double values are formatted with toString instead of NumberFormat.format().

⚙️ Config

Set ignored-invocations (default is none) to ignore toString calls inside a specific invocation.

dart_code_metrics:
  ...
  rules:
    ...
    - prefer-number-format:
        ignored-invocations:
           - someInvocation

Example

❌ Bad:

void main() {
  const int intValue = 5;
  const double doubleValue = 5;
  const num numValue = 5;

  final intString = intValue.toString(); // LINT
  final doubleString = doubleValue.toString(); // LINT
  final numString = numValue.toString(); // LINT

  final intString2 = '$intValue $5'; // LINT
  final doubleString2 = '$doubleValue $5.1'; // LINT
  final numString2 = '$numValue'; // LINT
}

✅ Good:

void main() {
  const int intValue = 5;
  const double doubleValue = 5;
  const num numValue = 5;

  final intString = NumberFormat().format(intValue);
  final doubleString = NumberFormat().format(doubleValue);
  final numString = NumberFormat().format(numValue);
}