Re: The symbol `@' and sexp scanning

[Michael Heerdegen <michael_heerdegen@web.de>]

Hello Andreas,

(we are talking about bug#24542")

> I believe the answer is in here:
>
> ,----[ (info "(elisp) Syntax Flags") ]
> |    • ‘p’ identifies an additional prefix character for Lisp syntax.
> |      These characters are treated as whitespace when they appear
> |      between 
> |      expressions.  When they appear within an expression, they are
> |      handled according to their usual syntax classes.
> `----

FWIW, I can't make much sense out of this description (but the first
sentence).  Nearly anything in an Elisp buffer is inside an expression.
Anything else is either a comment.  Or, the only case that seems to fit
into this description is an isolated "@" at top-level.  According to
this text, it should be treated as whitespace.  Dunno what that exactly
means, but evaluating something like that results in an error saying
that the symbol `@' is unbound, so it doesn't seem to be treated as
whitespace, but as an expression.

> This flag is set in elisp buffers.  But after evaluating
> (modify-syntax-entry ?@ "_") the function performs as expected.

Ok, but I guess it's not syntax classification that is problematic but
how it is treated in the case of the bug.  Also see the seemingly very
related bug#22238, btw.


Regards,

Michael.