Cascade Notation (..) trong Dart

🎯 Mục tiêu: Chain operations trên cùng object.

💡 Cú pháp


var button = Button()
  ..text = "Click me"
  ..color = Colors.blue
  ..onClick = handleClick;
 
// Tương đương
var button = Button();
button.text = "Click me";
button.color = Colors.blue;
button.onClick = handleClick;

📝 Với method calls


var list = <int>[]
  ..add(1)
  ..add(2)
  ..add(3)
  ..shuffle();

🔧 Null-aware cascade (?..)`


Button? button;
button
  ?..text = "Click"
  ..color = Colors.red;

📱 Trong Flutter


final controller = TextEditingController()
  ..text = "Initial"
  ..selection = TextSelection.collapsed(offset: 0)
  ..addListener(() => print("Changed"));

✅ Checklist

.. returns the object, not the result
Useful for builders/initialization
?.. for nullable objects