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RE: Emacs Lisp's future


From: Drew Adams
Subject: RE: Emacs Lisp's future
Date: Fri, 10 Oct 2014 15:56:40 -0700 (PDT)

> > Richard Stallman <address@hidden> writes:
> >> Do you mean text properties in strings, as in Emacs Lisp?
> > Yes.
> >
> > Having mulled it over, I've come to the conclusion that we can add
> > text properties to Guile strings...with the following caveat: text
> > properties must be invisible to all existing Scheme procedures,
> > including 'equal?' and 'write'....
> >
> > we could, in principle, use object-properties to associate text
> > properties with the characters themselves, instead of with the
> > string objects.  This would quite naturally lead to them being
> > copied by string operations such as 'substring' and 'string-
> > append'.
> 
> ...you mean something like this?
>   (define elisp-properties (make-object-property))
>   (define (elisp-propertize string . args)
>     (let ((copied-string (string-copy string)))
>       (set! (elisp-properties copied-string) args)
>       copied-string))
>   (define my-monkey (elisp-propertize "monkey" 'eats 'bananas))
>   (elisp-properties my-monkey) ;; => (eats bananas)

How would this relate to a future Guile implementation of
Emacs-Lisp text (and overlay) properties, whose values can be
arbitrary Emacs-Lisp thingies?

I know this question jumps the gun, but can we assume that if
an Emacs user puts an arbitrary Lisp thing (e.g., a particular
cons) on some text as a text-property value that that will carry
through to the Scheme implementation in such a way that s?he
can still manipulate the data of that value (e.g. modify the
particular cons cell components)?

IOW, will an Emacs user have the same abilities, and see the
same behavior, wrt text and overlay properties as s?he has and
sees now with Emacs Lisp?



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