typedef

 /// typedef

/// Syntax 1 : typedef return_type function_name(parameters);
/// Syntax 2 : typedef variable_name = return_type function_name;

// typedef Temp(int a);
//
// First(int a) {
//   print("First Function: ${a + 1}");
// }
// Second(int a) {
//   print("Second Function: ${a + 2}");
// }
// void main() {
//   Temp x = First;
//   x(5);
//
//   x = Second;
//   x(5);
// }

void main() {
  PerformOperation performOperation;
  performOperation = sumOfNumber;

  print(performOperation(n1: 2, n2: 5,),);

  performOperation = subOfNumber;

  print(performOperation(n1: 2, n2: 5,),);
}
/// typedef function_name(var args)
typedef PerformOperation({required int n1, required int n2});

double sumOfNumber({required int n1, required int n2}) {
  int sum = n1 + n2;
  return sum.toDouble();
}

double subOfNumber({required int n1, required int n2}) {
  int sub = n1 - n2;
  return sub.toDouble();
}