Re: Non-descriptive error-message

[Pavel Janík]

   From: Richard Stallman <address@hidden>
   Date: Wed, 7 Nov 2001 21:53:09 -0700 (MST)

   >      (setq expr (read (current-buffer)))
   > 
   >     How do I properly catch an error here and report it to user in the 
same way
   >     read signals "End of file during parsing" error?
   > 
   > You can use `condition-case' around the call to `read':
   > 
   >     (condition-case error-data
   >         (read)
   >       (error ...))

Of course, but then I can not signal an error *in the same way* to the
user. error will pop-up the debugger, but after simple

emacs -q -f eval-print-last-sexp 

you see only "End of file during parsing" message in the
echo-area. No debugger. I think we should use the same semantics here so
the user is not confused (he could press C-j accidentally).

   > See the Emacs Lisp Manual for details.  Note that there is currently
   > no way to distinguish end of file from other read errors except to
   > look at error-data.  Maybe it is better to check explicitly for the
   > just-whitespace case before calling read.

Something like this?

    (narrow-to-region (point-min) opoint)
+   (if (string-match (buffer-string) "[^ \t\n]")
+       (error "No expression to evaluate"))
    (setq expr (read (current-buffer)))

But this also does not signal an error the same way as I wrote
above. Do you see the solution?
-- 
Pavel Janík

Use the fundamental control flow constructs.
                  --  The Elements of Programming Style (Kernighan & Plaugher)