Re: Namespace protection from libguile

[Russ McManus <russell.mcmanus@gs.com>]

> I found this in the archives:
> 
>         ;;save current module
>         (define top (current-module))
>         (define x 1)
>         x ; yields 1
> 
>         ;;create and switch to a new module, called (foo bar)
>         (define-module (foo bar))
>         (define x 2)
>         x ; yields 2
> 
>         ;;switch back to the initial module
>         (set-current-module top)
>         x ; yields 1 again
> 
> Of course it doesn't really work, because inside "foo", "top"
> will be unbound. But looks like a cool way to achieve namespace
> protection.

This isn't good Scheme, since it potentially munches the-root-module's
namespace, but with a slight variation it works, and makes the point:

;;save current module
(module-define! the-root-module 'top (current-module))
(define x 1)
x ; yields 1

;;create and switch to a new module, called (foo bar)
(define-module (foo bar))
(define x 2)
x ; yields 2

;;switch back to the initial module
(set-current-module (module-ref the-root-module 'top))
x ; yields 1 again

> The questions are: is there a way to make this work on scheme?
> (Probably by making "foo" able to access toplevel symbol "top")

See above attempt.

> And more important, is there a way to make this work on C
> (libguile)? Are there functions that do the job of
> current-module, define-module and set-current-module?

When forced into such ugliness, I resort to gh_eval_str (blech).

> I really hesitate to use this method because Godot may render it
> completely useless, but I do have to use _something_ for now :-)
> and this one sounds better than the other sollution someone
> offered me (apart from the fact that I lost the message with
> this alternative sollution).

I've learned not to wait.

-russ

--
 "Unfortunately the only Windows feature inspired by Emacs was size."
             -- Nick C. in alt.religion.emacs