Snippet 5: Conditional access

main.dart

// Conditional access is a handy way to
// tighten up code that needs to read
// properties that could be null:
//
//   a?.b
// 
// The expression above evaluates to the
// value of `b` as long as `a` isn’t
// null. If `a` is null, then the expression
// evaluates to null. Try using conditional
// access to fix this code.

class BigThing {
  LittleThing little = LittleThing();
}

class LittleThing {
  int fetchInt() => 12;
}

void main() {
  final BigThing? big = BigThing();
  
  print('The value is:');
  print(big.little.fetchInt());
}

// Without null safety, *two* conditional
// access operators are needed for this
// code to work (one after `big` and one
// after `little`). With null safety,
// conditional access can short-circuit,
// so this expression only requires a
// single `?`.