RE: Emacs version and LISP interpretation

[Drew Adams]

> > version "Invalid escape character syntax".  I was able to trace it
> > down to instances like (insert ?\s). My PC will insert a 
> space and on
> 
> ?\s is a "new" syntax for the space character, introduced in Emacs-22.

So the answer is that you need to change (insert ?\s) to (insert ?\s ).  That
is, leave at least one space after the \s.

IMHO, the Emacs source code should itself leave such a space anyway, so that it
wouldn't gratuitously break backward compatibility this way.  What's the big
cost - one space char?

But backward compatibility is such a low (read non) priority for Emacs Dev that
it seems code was intentionally changed from "... ?\s )" to just "... ?\s)".
Inconsiderate, IMHO.

I've seen more than one library broken this way (broken for older Emacs
versions).  By that I mean that *ONLY* this change was made - there was no other
recent feature used that would otherwise invalidate use with an older version.
(No, I don't remember which libraries now.)