Can you explain the internal mechanics of how extensions work in the system?

In Flutter, extensions allow adding new methods and properties to existing classes without the need for inheritance or modifying the original class code. This is syntactic sugar that helps make the code more readable and convenient.

Internally, extensions are compiled into static methods that are called with the object passed as a parameter. This means that extensions do not modify the class itself but only provide additional functionality through external functions.

Example of an extension in Dart:

extension NumberParsing on String {
  int toInt() {
    return int.parse(this);
  }
}

void main() {
  String s = "123";
  print(s.toInt()); // Outputs 123
}

Here, the toInt method is added to the String type without changing the String class itself.