File local variable name containing ':'

File local variable name containing ':'

[Dan Davison]

I think it isn't possible to use a Local Variables line to set the value
of a variable whose name contains a colon . E.g. something like

# Local Variables:
# var:name: value
# End:

doesn't work because of the colon in var:name.

Assuming I'm not overlooking an easy workaround, it seems that one
possible fix would be to recognise the separator character on-the-fly as
the character following the word "Variables". For what it's worth, I did
have a go at making that change (below). Could this behaviour be changed
or is this a limitation that's here to stay?

Dan

--8<---------------cut here---------------start------------->8---
diff --git a/lisp/files.el b/lisp/files.el
index 3d9dd90..68ba1f0 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3053,7 +3053,7 @@ If MODE-ONLY is non-nil, all we do is check whether the major mode
 is specified, returning t if it is specified."
   (let ((enable-local-variables
 	 (and local-enable-local-variables enable-local-variables))
-	result)
+	result separator)
     (unless mode-only
       (setq file-local-variables-alist nil)
       (report-errors "Directory-local variables error: %s"
@@ -3066,10 +3066,11 @@ is specified, returning t if it is specified."
 	(search-backward "\n\^L" (max (- (point-max) 3000) (point-min))
 			 'move)
 	(when (let ((case-fold-search t))
-		(search-forward "Local Variables:" nil t))
+		(re-search-forward "Local Variables\\([^ \t\n]\\)" nil t))
+	  (setq separator (match-string 1))
 	  (skip-chars-forward " \t")
-	  ;; suffix is what comes after "local variables:" in its line.
-	  ;; prefix is what comes before "local variables:" in its line.
+	  ;; suffix is what comes after "local variables<SEPARATOR>" in its line.
+	  ;; prefix is what comes before "local variables<SEPARATOR>" in its line.
 	  (let ((suffix
 		 (concat
 		  (regexp-quote (buffer-substring (point)
@@ -3088,7 +3089,7 @@ is specified, returning t if it is specified."
 	      (save-excursion
 		(unless (let ((case-fold-search t))
 			  (re-search-forward
-			   (concat prefix "[ \t]*End:[ \t]*" suffix)
+			   (concat prefix "[ \t]*End" separator "[ \t]*" suffix)
 			   nil t))
                   ;; This used to be an error, but really all it means is
                   ;; that this may simply not be a local-variables section,
@@ -3118,15 +3119,15 @@ is specified, returning t if it is specified."
 		  ;; Find the variable name; strip whitespace.
 		  (skip-chars-forward " \t")
 		  (setq beg (point))
-		  (skip-chars-forward "^:\n")
-		  (if (eolp) (error "Missing colon in local variables entry"))
+		  (skip-chars-forward (concat "^\n" separator))
+		  (if (eolp) (error "Missing separator character in local variables entry"))
 		  (skip-chars-backward " \t")
 		  (let* ((str (buffer-substring beg (point)))
 			 (var (let ((read-circle nil))
 				(read str)))
 			 val)
 		    ;; Read the variable value.
-		    (skip-chars-forward "^:")
+		    (skip-chars-forward (concat "^" separator))
 		    (forward-char 1)
 		    (let ((read-circle nil))
 		      (setq val (read (current-buffer))))
--8<---------------cut here---------------end--------------->8---

Re: File local variable name containing ':'

[Andreas Schwab]

Dan Davison <davison@stats.ox.ac.uk> writes:

> @@ -3088,7 +3089,7 @@ is specified, returning t if it is specified."
>  	      (save-excursion
>  		(unless (let ((case-fold-search t))
>  			  (re-search-forward
> -			   (concat prefix "[ \t]*End:[ \t]*" suffix)
> +			   (concat prefix "[ \t]*End" separator "[ \t]*" suffix)
                                               (regexp-quote separator)

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: File local variable name containing ':'

[Stefan Monnier]

> I think it isn't possible to use a Local Variables line to set the value
> of a variable whose name contains a colon . E.g. something like

Indeed, it looks like you're right.

> Assuming I'm not overlooking an easy workaround, it seems that one
> possible fix would be to recognise the separator character on-the-fly as
> the character following the word "Variables".

That makes the check for the presence of file-local variables even
more loose.  I.e. a file that contained "Local Variables" but not "Local
Variables:" will now be considered as containing file-local variables
and will likely generate an error about missing "End" when you try and
open the file.

The current "Local Variables:" pattern is already much too loose in my
opinion, so I'm definitely not going to let it become even more permissive.


        Stefan

Re: File local variable name containing ':'

[Dan Davison]

Stefan Monnier <monnier@IRO.UMontreal.CA> writes:

>> I think it isn't possible to use a Local Variables line to set the value
>> of a variable whose name contains a colon . E.g. something like
>
> Indeed, it looks like you're right.
>
>> Assuming I'm not overlooking an easy workaround, it seems that one
>> possible fix would be to recognise the separator character on-the-fly as
>> the character following the word "Variables".
>
> That makes the check for the presence of file-local variables even
> more loose.  I.e. a file that contained "Local Variables" but not "Local
> Variables:" will now be considered as containing file-local variables
> and will likely generate an error about missing "End" when you try and
> open the file.
>
> The current "Local Variables:" pattern is already much too loose in my
> opinion, so I'm definitely not going to let it become even more permissive.

Fair enough. What about requiring that the separating colon is followed
by whitespace. Is the backwards incompatibility cost too high there? Or
could colons in the variable name be escaped with a backslash?

Dan

>
>
>         Stefan

Re: File local variable name containing ':'

[Stefan Monnier]

> Fair enough. What about requiring that the separating colon is followed
> by whitespace. Is the backwards incompatibility cost too high there?

We could do that.  E.g. if there's only 1 colon, we know what to do, and
if there's more than 1 we can force the separating one to be followed by
something like [[ "(].

> Or could colons in the variable name be escaped with a backslash?

That would be a good simple and reliable option, indeed, since a\:b
already represents the same symbol as a:b in Elisp.


        Stefan