Records, Patterns & Primary Constructors

Treat Records, Patterns & Primary Constructors as a contract for static types, nullability, mutability, equality, destructuring, and data shape—not merely syntax. Prefer compiler promotion and immutable values over casual use of dynamic or !.

Build a Complete Mental Model

Treat Records, Patterns & Primary Constructors as a contract for static types, nullability, mutability, equality, destructuring, and data shape—not merely syntax. Prefer compiler promotion and immutable values over casual use of dynamic or !.

Apply It in Modern Dart

Run and test an original Records, Patterns & Primary Constructors example with null, empty, boundary, invalid, async-error, and cancellation cases. Use dart format, dart analyze, and dart test, and verify Future or Stream subscriptions and isolate boundaries where relevant.

After This Lesson

• Explain nullability, mutability, and async contracts
• Write an example that passes dart analyze
• Test a failure or async case

class Point(final int x, final int y);

void main() {
  final point = Point(3, 4);
  final pair = (point.x, point.y);
  final (x, y) = pair;
  print('x=$x, y=$y');
}

x=3, y=4

Dart primary constructors — Dart