While add-to-list often works with lexical variables, this is a hack
that isn't always effective; better tell the user not to try.
* doc/lispref/lists.texi (List Variables): Add a note about lexical
variables to the add-to-list description. Fix the equivalent code.
* lisp/subr.el (add-to-list): Amend doc string.
The argument @var{symbol} is not implicitly quoted; @code{add-to-list}
is an ordinary function, like @code{set} and unlike @code{setq}. Quote
the argument yourself if that is what you want.
+
+Do not use this function when @var{symbol} refers to a lexical
+variable.
@end defun
Here's a scenario showing how to use @code{add-to-list}:
@var{value})} is this:
@example
-(or (member @var{value} @var{var})
- (setq @var{var} (cons @var{value} @var{var})))
+(if (member @var{value} @var{var})
+ @var{var}
+ (setq @var{var} (cons @var{value} @var{var})))
@end example
@defun add-to-ordered-list symbol element &optional order
If ELEMENT is added, it is added at the beginning of the list,
unless the optional argument APPEND is non-nil, in which case
ELEMENT is added at the end.
+LIST-VAR should not refer to a lexical variable.
The return value is the new value of LIST-VAR.