Comments on: Multiple stores in Elephant

By: Leslie

Leslie — Fri, 08 Feb 2008 16:51:06 +0000

Problematic if you’re developing and closing the store somewhere in between. Who will open it again?

By: Johannes (hnaz) Weiner

Johannes (hnaz) Weiner — Fri, 08 Feb 2008 16:30:11 +0000

Hi,

– quote –
(defvar *item-sc* nil) ; newbies note that DEFVAR only assigns to non-existing variables
(when (null *item-sc*)
(setf *item-sc* (elephant:open-store *item-store*)) ; *item-store* defined elsewhere
– /quote –

If your comment to newbies is true, how about

(defvar *item-sc* (elephant:open-store *item-store*)))

then? :)

By: Leslie

Leslie — Fri, 08 Feb 2008 09:04:53 +0000

I haven’t looked it up in the CLHS (“Caveat emptor”, as Kent Pitman likes to say). Let’s do it now:

“defparameter and defvar establish name as a dynamic variable.”

Yes, you’re right :)

Thanks, Mikael; I’m going to change the post to reflect that.

By: Mikael Jansson

Mikael Jansson — Thu, 07 Feb 2008 21:53:41 +0000

Are you /really/ sure you need (declare (special *store-controller*))?

If *store-controller* is defined using either DEFVAR or DEFPARAMETER, you don’t need to declare it special, rebinding it with LET will suffice.

By: Thom

Thom — Thu, 07 Feb 2008 16:46:59 +0000

Honestly, I read that as, “If you’re interested in more Elephant droppings, post a short comment.”

Anyway, yes, I am too am interested in more Elephant posts.

By: jfm3

jfm3 — Thu, 07 Feb 2008 16:37:33 +0000

This post shows how to manage special variables with unruly scope by hiding them behind an interface that guarantees good behavior, and by declaring special local variables. It subtly makes the case that special variables really are “globals done right.”

I’m interested in Elephant too. Thanks for the post!

By: Alec

Alec — Thu, 07 Feb 2008 15:31:06 +0000

I am interested in more Elephant posts.