RE: Advice on ST-Object data-structure setup

[Maxime Devos <maximedevos@telenet.be>]

>is to get the mechanics working.  For this I 
> need to have an St-Object which is basically a Vector but which 
> answers #false to vector? and #true to st-object?
>
> [Note https://github.com/KenDickey/Crosstalk/blob/master/st-kernel.scm ]
>
> I note that one might change the T7 type-tag from 0x0d (vector) to 
> 0x6d (currently unused) with a quick bitwise-or, but would like some 
> advice on the best way to do this or some alternate.  I would prefer 
> to work in Scheme, not C, BTW.

It would be simplest to define a record type with a single field, let’s say ‘<st-vectorlike>’ with a field ‘actual-vector’(*)

(*) plus whatever fields are required to make it satisfy ‘st-object?’

The objects of type <st-vectorlike> are by construction not vectors (so, they don’t satisfy vector?). However, you can easily define

;; st-vector-ref: rename this to the equivalent of vector-ref in Smalltalk,
;; and replace ‘define’ by what would be the equivalent in Smalltalk
(define (st-vector-ref v n)
  ;; st-vector-like-actual-vector: field getter
  ;; vector-ref: standard Scheme procedure
  (vector-ref (st-vector-like-actual-vector v) n))

and the like.

Best regards,
Maxime Devos.