Classes, Enums, Extensions
Extensions
Add a Method to a Type
An extension on T adds methods callable on values of type T, without subclassing or wrapping.
Program
Play the program to call a custom shout on a plain String.
extensions.dart
extension StringExtras on String {
String shout() => toUpperCase() + '!';
}
void main() {
var greeting = 'hello';
print(greeting.shout());
}
extension
`extension Name on T { ... }` adds members to type `T`.
dot call
`greeting.shout()` looks like a normal method call.
no subclass
Extensions do not require subclassing or wrapping.