Ar an séiú lá de mí na Nollaig, scríobh Uwe Brauer: I suspect (unless (featurep 'xemacs) ;; GNU Emacs-specific code goes here ) is probably the simplest, clearest, most effective way to write that sort of code today. I will be surprised and astonished if your init file has to run on Lucid Emacs. -- I AM IN JAIL AND ALLOWED SEND ONLY ONE CABLE SINCE WAS ARRESTED WHILE MEASURING FIFTEEN FOOT WALL OUTSIDE PALACE AND HAVE JUST FINISHED COUNTING THIRTY EIGHT THOUSAND FIVE HUNDERED TWENTY TWO NAMES WHOS WHO IN MIDEAST.

Uwe> Ok, I think I go for that, but isn't it that unless is Uwe> relative recent and (if (not (featurep 'xemacs) might be the Uwe> more robust solution. `when' and `unless' have been in C in XEmacs since 1995 or so. GNU Emacs was a little more conservative, but for practical purposes there's so much code that uses them, they're pretty sure to be available in your environment. -- School of Systems and Information Engineering http://turnbull.sk.tsukuba.ac.jp University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN Ask not how you can "do" free software business; ask what your business can "do for" free software.

Reiner> Test for features (`featurep') , functions (`fboundp') or Reiner> variables (`boundp') instead of versions. You can test for symbols with `intern-soft', though that is rarely useful in this context. -- School of Systems and Information Engineering http://turnbull.sk.tsukuba.ac.jp University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN Ask not how you can "do" free software business; ask what your business can "do for" free software.

Reiner> (when (featurep 'xemacs) Reiner> xemacs-code) Reiner> (unless (featurep 'xemacs) Reiner> emacs-code) Reiner> (if (featurep 'xemacs) Reiner> xemacs-code Reiner> emacs-code) What are the specific reason to use `when', if `if' exists? Just convenience? (I also thought that `when' is more recent then `if') Reiner> IMHO: No. The byte compiler of Emacs is able to ignore the Reiner> (featurep 'xemacs) parts when compiling with Emacs. I Reiner> don't know if XEmacs byte compiler has the same feature. Ok, that is a interesting point. Reiner> Test for features (`featurep') , functions (`fboundp') or variables Reiner> (`boundp') instead of versions. Ok, thanks Uwe

Reiner> On Wed, Dec 07 2005, Uwe Brauer wrote: >> >> Reiner> Convenience and readability (YMMV): Reiner> ;; ugly: Reiner> (if (featurep 'xemacs) Reiner> (progn Reiner> xemacs-code-0 Reiner> xemacs-code-1 Reiner> xemacs-code-N)) Ok I see, that is the way I thought about it, use progn and () (I don't find that ugly but I see the point)