[Lispweb] IMHO: popup-list

[Marco Antoniotti]

> From: mdanish at andrew.cmu.edu
> Cc: lispweb at red-bean.com
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> Date: Mon, 25 Feb 2002 23:34:01 -0500
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> On Mon, Feb 25, 2002 at 10:12:14PM -0500, Erik Enge wrote:
> > Hi, gang.
> > 
> > I want to use the popup-list form-element IMHO offers.  In the
> > documentation of the initarg items, it says:
> > 
> >          assoc list, or function returning alist, of items appearing
> >          in the list
> > 
> > Fine.  So, I assume, then, that this should work:
> > 
> >         (defun some-items ()
> >          '(("1" . ("2" . ()))))
> > 
> >         (resources
> >          :type popup-list
> >          :initargs (:items #'some-items))
> > 
> > However, I get the error message:
> > 
> > 
> >         Type-error in KERNEL::OBJECT-NOT-LIST-ERROR-HANDLER:
> >          FUNCTION is not of type LIST
> > 
> > From the source (form-elements.lisp) I can tell that one does not even
> > look to see if the slot items can contain a function and assumes it is
> > a list (which explains the error).
> > 
> > So, which is right, documentation or code?  Patches accepted?
> 
> Code, of course =)
> 
> I've always used a-lists of the form 
> 
> ((:item-1 "Item 1") (:item-2 "Item 2") ...)
> 
> and never had trouble with it.  Your example a-list doesn't look like one,
> btw.

Please note that your example of an a-list is also somewhat
misleading.

cl-prompt> (defvar *al* '((:item-1 "Item 1") (:item-2 "Item 2")))
*AL*
cl-prompt> (assoc :item-2 *al* :test #'eq)
("Item 1")

I.e. an a-list is always to be thought as

     ((item1 . content1) (item2 . content2) ...)

Anyway, this begs the question: why a-lists and not HASH-TABLEs?

Cheers

-- 
Marco Antoniotti ========================================================
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