Re: New VSI post on Youtube

On 8/24/2024 9:33 PM, Stephen Hoffman wrote:

On 2024-08-20 12:36:51 +0000, Simon Clubley said:

One thing I wish was available in all languages is the ability to return multiple values from a function call so you can return both a status and the value(s) in one assignment. Ie: "a, b, c = demo_function(param1, param2);".
>
In languages with dynamic associative arrays (such as PHP), I simulate this by returning an associative array from a function call with both status and value fields. Makes coding _so_ much cleaner and robust.

 For those following along at home, C supports returning a struct.
 Languages including Swift allow returning an "optional", where you either get a value such as an object, or an indication or its absence. Swift uses the concept of "unwrapping" a result marked optional, which means you have to check before access.
 Returning objects is more widely available, and hides a lot of this mess, as well as hiding dealing with potentially-larger data buffers. Objects and message-passing is akin to itemlist-based APIs, dragged forward a few decades.
 In other languages, support for an optional requires explicit code, whether that might return a struct, or might return a value and a sentinel, or ilk.

I don't know Swift but I will assume Swift optional is similar to
optional in other languages.
It solves the return both status and value problem. But it is
not a general multiple return value solution. And it is really
just a small evolution of the traditional "return null
indicate an error".
$ type OptionalDemo.java
import java.util.Optional;
public class OptionalDemo {
     public static String oldStyleAPI(int v) {
         if(v > 0) {
             return Integer.toString(v);
         } else {
             return null;
         }
     }
     public static Optional<String> newStyleAPI(int v) {
         if(v > 0) {
             return Optional.of(Integer.toString(v));
         } else {
             return Optional.empty();
         }
     }
     public static void testOldStyleAPI(int v) {
         String s = oldStyleAPI(v);
         if(s != null) {
             System.out.println(s);
         } else {
             System.out.println("No result");
         }
     }
     public static void testNewStyleAPI(int v) {
         Optional<String> s = newStyleAPI(v);
         if(s.isPresent()) {
             System.out.println(s.get());
         } else {
             System.out.println("No result");
         }
     }
     public static void testNewStyleAPISmarter(int v) {
         Optional<String> s = newStyleAPI(v);
         System.out.println(s.orElse("No result"));
     }
     public static void main(String[] args) {
         testOldStyleAPI(123);
         testOldStyleAPI(0);
         testNewStyleAPI(123);
         testNewStyleAPI(0);
         testNewStyleAPISmarter(123);
         testNewStyleAPISmarter(0);
     }
}
$ javac OptionalDemo.java
$ java "OptionalDemo"
123
No result
123
No result
123
No result
Arne