Re: Documentation not clear for the Lisp function set-variable

[Juanma Barranquero]

> The patch below modifies `user-variable-p' [etc, etc.]

That would be more convincing if I really attached the patch...

(BTW, the patch uses diff -b because most of user-visible-p is now
inside a while loop, but otherwise unchanged.)

-- 
                    /L/e/k/t/u


Index: src/eval.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/eval.c,v
retrieving revision 1.246
diff -b -c -2 -r1.246 eval.c
*** src/eval.c  28 Jun 2005 02:27:38 -0000      1.246
--- src/eval.c  28 Jun 2005 08:34:08 -0000
***************
*** 890,899 ****
  }
  
  DEFUN ("user-variable-p", Fuser_variable_p, Suser_variable_p, 1, 1, 0,
!        doc: /* Returns t if VARIABLE is intended to be set and
modified by users.
  \(The alternative is a variable used internally in a Lisp program.)
! Determined by whether the first character of the documentation
! for the variable is `*' or if the variable is customizable (has a non-nil
! value of `standard-value' or of `custom-autoload' on its property list).  */)
       (variable)
       Lisp_Object variable;
--- 890,911 ----
  }
  
+ /* Error handler used in Fuser_variable_p.  */
+ static Lisp_Object
+ user_variable_p_eh (ignore)
+      Lisp_Object ignore;
+ {
+   return Qnil;
+ }
+ 
  DEFUN ("user-variable-p", Fuser_variable_p, Suser_variable_p, 1, 1, 0,
!        doc: /* Return t if VARIABLE is intended to be set and
modified by users.
  \(The alternative is a variable used internally in a Lisp program.)
! A variable is a user variable if
! \(1) the first character of its documentation is `*', or
! \(2) it is customizable (its property list contains a non-nil value
!     of `standard-value' or `custom-autoload'), or
! \(3) it is an alias for another user variable.
! Return nil if VARIABLE is an alias and there is a loop in the
! chain of symbols.  */)
       (variable)
       Lisp_Object variable;
***************
*** 904,907 ****
--- 916,927 ----
        return Qnil;
  
+   /* If indirect and there's an alias loop, don't check anything else.  */
+   if (XSYMBOL (variable)->indirect_variable
+       && NILP (internal_condition_case_1 (indirect_variable, variable,
+                                           Qt, user_variable_p_eh)))
+     return Qnil;
+ 
+   while (1)
+     {
        documentation = Fget (variable, Qvariable_documentation);
        if (INTEGERP (documentation) && XINT (documentation) < 0)
***************
*** 920,924 ****
--- 940,950 ----
            || (!NILP (Fget (variable, intern ("custom-autoload")))))
          return Qt;
+ 
+       if (!XSYMBOL (variable)->indirect_variable)
          return Qnil;
+ 
+       /* An indirect variable?  Let's follow the chain.  */
+       variable = XSYMBOL (variable)->value;
+     }
  }