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Re: Lisp help: problem with uninterned symbols


From: Lars Brinkhoff
Subject: Re: Lisp help: problem with uninterned symbols
Date: 12 Dec 2003 22:59:32 +0100
User-agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/20.7

Pascal Bourguignon <address@hidden> writes:
> One question: why don't you use an obarray for you symbols?

I may do that I the future, but one problem (I believe) is that it's
not possible to intern the same symbol in more than one obarray.

> (I doubt that would change anything thought).

No, I don't think so.

> Otherwise, I'm afraid you'll have to extend the emacs byte compiler
> to allow it to work with various sources of "interned" symbols.

Something like Common Lisp's load-time-value would be nice.  My
problem would then be solved by wrapping (load-time-value ...) around
the difficult parts.

Building on Stefan's suggestion, how about this?

  (defvar load-time-value-list)
  
  (defmacro start-load-time-values ()
    "This macro must be called before the first use of load-time-value."
    (setq load-time-value-list nil))
  
  (defmacro end-load-time-values ()
    "This macro must be called after the last use of load-time-value."
    `(progn ,@(mapcar (lambda (x) `(defvar ,@x))
                      load-time-value-list)))
  
  (defmacro load-time-value (form &optional read-only-p)
    (if byte-compile-current-form
        (let ((sym (gentemp)))
          (push (list sym form) load-time-value-list)
          sym)
        form))

Note the use of gentemp instead of gensym.

-- 
Lars Brinkhoff,         Services for Unix, Linux, GCC, HTTP
Brinkhoff Consulting    http://www.brinkhoff.se/





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