How do you pass by reference in Flutter?

Passing Data by Reference in Flutter

In Flutter, passing data by reference involves passing a reference of an object (such as a class instance) from one widget to another. Since Dart (the programming language of Flutter) is pass-by-value, the "reference" you pass is essentially a copy of a reference, not a true reference as in languages like C++. This means you're still working with the same object but in a new context.

Example:

    
class Person {
  String name;
  int age;

  Person(this.name, this.age);
}

class ParentWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    Person person = Person('Alice', 25);

    return ChildWidget(person: person);
  }
}

class ChildWidget extends StatelessWidget {
  final Person person;

  ChildWidget({required this.person});

  @override
  Widget build(BuildContext context) {
    return Text('Name: \${person.name}, Age: \${person.age}');
  }
}
    
  

In this example, the Person instance created in the ParentWidget is passed as an argument to the ChildWidget. Although the person object is copied, it still refers to the same memory location, so any changes made to it in the ChildWidget will be reflected in the Person instance in the ParentWidget.

Important Points:

• Passing by reference in Dart means you're still working with the same object, not a duplicate.
• If you modify the object's properties (like name or age), the changes will be reflected everywhere it's referenced.
• Passing by reference applies only to objects (classes), not primitive types like numbers or strings.

Remember that Dart's garbage collector will manage memory, so you don't need to worry about memory management directly.

Passing data by reference is a fundamental concept in Flutter, allowing widgets to communicate and share data without duplicating memory usage.