CODEWITHSUNDEEP
emacs
Sean Perry
Sean Perry

Reputation: 3886

How do I support multiple versions of Emacs config when a variable becomes obsolete?

I share my Emacs config across numerous computers. Some of them I can easily maintain my own copy of emacs and on others I do not have that luxury. I am seeing the following message:

'disabled-command-hook' is an obsolete variable (as of Emacs 22.1); use 'disabled-command-function'

This occurs at startup because I have my config set to byte-compile any files that are not already compiled. Problem is, I still have one or two Emacs 21 instances. How do I support both the old and the new? My google-fu is not working for me.

I tried using this macro:

(defmacro WhenEmacsOlderThan (major minor &rest body)
   `(if (or (< emacs-major-version ,major) (and (= emacs-major-version ,major)
                                                                           (< emacs-minor-version ,minor)))
      (progn ,@body)
     nil
    )
 )

Which looks like this in use:

(WhenEmacsOlderThan 22 1
   (setq disabled-command-hook nil)
 )

But I still see the message in the newer Emacs versions about the obsolete variable. What am I missing?

I have found other questions like this but the goal was to hide the message. I want to understand why I am seeing the message and how to avoid the problem in a cross-version compatible way.

Thanks.

Upvotes: 1

Views: 434

Answers (2)

Stefan
Stefan

Reputation: 28521

The message is a warning, so your (setq disabled-command-hook nil) will still work, but when that variable will be removed, the warning will also disappear, so better get ready. You can do:

(setq disabled-command-hook nil) ;; Obsolete since Emacs-22.
(setq disabled-command-function nil)

so it will work in all versions. You might also be able to avoid the warning with

(if (boundp 'disabled-command-hook)
    (setq disabled-command-hook nil)) ;; Obsolete since Emacs-22.
(setq disabled-command-function nil)

Upvotes: 2

Miserable Variable
Miserable Variable

Reputation: 28752

Can you instead directly check if the disabled-command-hook is obsolete? 

(defun make-obsolete (obsolete-name current-name &optional when)
  ....
  (put obsolete-name 'byte-obsolete-info

So maybe 

(if (not (get disabled-command-hook 'byte-obsolete-info))
  (setq disabled-command-hook nil))

Upvotes: 1

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