defvar and "special-variable-p"-ness

[Eduardo Ochs <eduardoochs@gmail.com>]

Hi list,

after "defvar"-ing a variable its "special-variable-p"-ness becomes
true. Is there a way to make its "special-variable-p"-ness nil again?
That would be useful for some tests that I am trying to write...

By the way, I thought that "unload-feature" would be able to revert
the "special-variable-p"-ness of a variable back to nil, but it seems
that it doesn't do that. Here's how I tested it. I created a file
"/tmp/myfile.el" with just these three lines,

  ;; Copy this 3-line block to /tmp/myfile.el
  (defvar myvar 99)
  (provide 'myfile)

Then I ran the uncommented sexps below one by one with my favorite
variant of `C-x C-e':

  (setq myvar 42)
  (special-variable-p 'myvar)
  ;; ^ --> nil

  (require 'myfile "/tmp/myfile.el")
  (assoc "/tmp/myfile.el" load-history)
  ;; ^ --> ("/tmp/myfile.el" myvar (provide . myfile))
  (special-variable-p 'myvar)
  ;; ^ --> t

  (unload-feature 'myfile)
  (assoc "/tmp/myfile.el" load-history)
  ;; ^ --> nil
  (special-variable-p 'myvar)
  ;; ^ --> t

Thanks in advance!
  Eduardo Ochs
  http://angg.twu.net/#eev
  http://angg.twu.net/eev-intros/find-lexical-intro.html