Named Parameters with Defaults

Named parameters live in {...}. Each can carry a default so the caller can omit it.

Program

Play the program to call a greeter with and without a named prefix.

named_params.dart

String greet(String name, {String prefix = 'Hello'}) {
  return '$prefix, $name!';
}

void main() {
  var a = greet('Ada');
  var b = greet('Lin', prefix: 'Hi');
  print('$a / $b');
}

named params Names in `{...}` are passed as `name: value`.

default `prefix = 'Hello'` is used when the caller omits `prefix`.

call site `greet('Lin', prefix: 'Hi')` mixes positional and named.