pass by value / pass by reference

pass by value / pass by reference

[Keisuke Nishida]

Hello,

One problem of my current implementation is that whenever one
interpreter calls the other one, the arguments are converted
into the other type; that is, they are passed by value.  This
works fine for some cases, but sometimes it is necessary to pass
them by reference.

Using some tricks, our Scheme files may look like this:

  ;; Import a variable from the lisp world.
  (import-lisp-variable user-full-name)

  ;; Get the value of variable by value.
  (define name (user-full-name))

  ;; Set the value of varialbe
  (set! (user-full-name) name)

  ;; Call a Lisp function with the reference of variable
  (insert user-full-name)

This looks nice and natural, but I wonder if this code can be used
in the future with the real Guile-based Emacs, where all values are
references...

But I guess this is an unavoidable drawback of my approach.
I have to do this in any event.  I understand I'm doing a bad thing...

Re: pass by value / pass by reference

[Keisuke Nishida]

Keisuke Nishida <kxn30@po.cwru.edu> writes:

> One problem of my current implementation is that whenever one
> interpreter calls the other one, the arguments are converted
> into the other type; that is, they are passed by value.  This
> works fine for some cases, but sometimes it is necessary to pass
> them by reference.

Not exactly.  I mean:

 [ Value Model ]

           scheme-eval            lisp-eval
  Lisp obj ----------> Scheme obj --------> Lisp obj


 [ Reference Model ]

           scheme-eval            lisp-eval
  Lisp obj ----------> Lisp ptr   --------> Lisp obj
                    (as Scheme obj)

So, we are going to import all Lisp objects as pointers.