Hi,

I'd like to offer an observation and make a request for the future development of Phrogram. In the recent program I wrote (Space Junk -- see elsewhere) I wanted to create new objects dynamically.  I know that there's the "New" keyword (as yet officially unsupported), but I wanted to play completely by the rules, so I used the following kind of pattern:

      Function NewObject() As MyClass
          Define result As MyClass
          Return result
      End Function

This does what I needed. However, as I've worked more with Phrogram I've realised that one of the concepts that seems to be missing is that of the "null" (or "nil", or "undefined") object. In some ways I can understand why, because if you have "null" then you'll have to handle things returning it, which adds some complication. That's why a variable definition in Phrogram (implicitly) calls a constructor to initialise the variable. But sometimes null is indispensible --- for example when you wish to indicate that a function that returns an object is returning an invalid value. The alternative is ugly -- having to add some kind of "I'm not really a valid object" member into class defintions, that then has to be explicitly set or reset.

What we need is a value that you can set variables to, and compare variables against, but which is otherwise invalid. I believe that especially when (if?) the "New" keyword is introduced, some concept of null will become essential.

Now, I have experimented a bit, and the following bit of code almost does what I need:

Program PseudoNull
      Define NULL As Any

      Method Main()
            Define s As String = "hello"           

            s = NULL
            If IsNull(s) Then
                  PrintLine("s is null")
            Else
                  PrintLine("s is NOT null")
            End If

            Define a As Integer[10]
            a = NULL
            If IsNull(a) Then
                  PrintLine("a is null")
            Else
                  PrintLine("a is NOT null")
            End If
      End Method

      Function IsNull(x As any) As Boolean
            Return x = NULL
      End Function
End Program

This compiles OK, but when you run it you get "Runtime error at line 8: Object reference not set to an instance of an object". That's true --- and is in fact exactly what I want ... but not to complain about it!

So, what does anyone else think? Are you with me in asking for the addition of "nothingness" to the Phrogram language?

Neil