Re: Possible defvar bug

[Alan Mackenzie <acm@muc.de>]

On Mon, Feb 18, 2013 at 04:00:28PM +0100, Didier Verna wrote:
> Jambunathan K <kjambunathan@gmail.com> wrote:

> > I am certain I don't understand what these paragraphs mean,
> > particularly the second one.
> > lands.

> > ,----  C-h f
> > | If SYMBOL has a local binding, then this form affects the local
> > | binding.  This is usually not what you want.  Thus, if you need to
> > | load a file defining variables, with this form or with `defconst' or
> > | `defcustom', you should always load that file _outside_ any bindings
> > | for these variables.  (`defconst' and `defcustom' behave similarly in
> > | this respect.)
> > `----

>   This means that:

> ELISP> (let ((foo 3))
> 	 (defvar foo 1)
> 	 (print foo))
> 3
> ELISP> foo
> *** Eval error ***  Symbol's value as variable is void: foo
> ELISP> 


> And, no, this is almost never what you want :-) Just like Tassilo
> noticed by accident.

Why would anybody want to defvar a variable inside a let binding which
also defines it, anyway?  It may not be totally invalid, but it's
certainly in breach of good taste.  I would argue that the current
behaviour _is_ what is wanted, since it alerts one to a probable error.

-- 
Alan Mackenzie (Nuremberg, Germany).