Proposal (was: [Lispweb] [ANN] UnCommon Web 0.2 - learning to walk) rm at
Tue Mar 2 12:34:54 CST 2004

On Tue, Mar 02, 2004 at 07:17:14PM +0100, Marco Baringer wrote:
> I think it's an excellent idea (sorta goes against the whole "code in 
> one place presentation elswhere" idea, but I'm still deciding about 
> that).

Well, i just got tired ouf having to build a deeply nested plist
that mirrors the objects i want to render -- the code has to walk
the object structure to create the plist which is then walked by the
tal function. 

> However, we'd need to define a tal enviroment api, would this 
> cover everything you need:
> (defgeneric lookup-tal-variable (name enviroment)
>   (:documentation "Return the value assciated with NAME (a
>   symbol) in the enviroment ENVIROMENT."))
> (defgeneric extend-tal-enviroment (new-env old-env)
>   (:documentation "Create a new enviroment with all the bindings
>   in both NEW-ENV and OLD-ENV. If both enviroments bind the same
>   names the bindings in NEW-ENV must shadow those in OLD-ENV."))
> (defgeneric add-binding (name value enviroment)
>   (:documentation "Create a new enviroment which is like
>   ENVIROMENT but also has VALUE bound to NAME."))

Ah, i see. So your code does in fact modify the environment. 
I guess i would imagine a stack based environment object with a generic
'fetch-value (name)'. A lookup would would apply this method to all
objects on the stack until successfull.

> This should be enough to genericly implement DOLIST and INCLUDE which 
> are, so far, the only tags i have which mess with the enviroment. It's 
> been implemented in yaclml--dev--0.4--patch-5.

Good ;-) I'll check it out.

> Makes me wonder if cacheable/lazy enviroments would be a good idea.

In certain cases i'd think so.

> p.s. - Would it be dificult to write an araneida backend for ucw?

Gosh, i'm not the person to ask this, just an araneida beginner myself
(desperately lokking for documentation) :-) I would be fine to have one
but i'm affraid i'm way too busy right now to hack one myself.



> -
> Marco
> Ring the bells that still can ring.
> Forget the perfect offering.
> There is a crack in everything.
> That's how the light gets in.
> 	-Leonard Cohen
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