[tbnl-devel] Question about dispatchers and their actions

[Edi Weitz]

On Fri, 23 Jul 2004 09:36:57 -0400, Pete Kazmier <pete-tbnl-dev at kazmier.com> wrote:

> On Fri, 2004-07-23 at 09:10, Stefan Scholl wrote:
>> But I think it should be an exception to the rule. Let the
>> handler return _two_ values if he is sure that the reason for not
>> processing the request is no fatal error and dispatching should
>> continue.
>> Normal handlers just return a string or nil if they have a
>> problem. Handlers which are aware of the possibility that other
>> dispatchers could catch the request when they fail return
>> (values nil t)
>
> Thats a good idea.  I keep forgetting about the usefulness of the
> ability to return multiple values.  With this ability, I would be
> able to minimize the complexity of my dispatch functions and move
> some of that logic into the handler itself which could then have the
> option of opting to not process the request (defer to the next
> dispatcher).

I'm not sure what would be the right way. At the moment it is not
specified what it means if a handler returns NIL so we could as well
implement Pete's initial idea to let the next dispatcher take over in
this case. Using a second return value would also be a possibility but
it would require more work in modlisp.lisp because the HANDLER-BIND
code already generates a second return value to denote errors.

> Out of curiousity, what do you guys like to use for generating your
> HTML?  Are you firm believers in the whole "separation of logic and
> presentation" and prefer the use of template engines?  Or do you
> prefer to output HTML from your TBNL apps and then let folks use CSS
> to adjust the presentation as they see fit?  Or do you use a
> combination of both?

I've written HTML-TEMPLATE for separation of logic and
presentation. Not because I think it's "the way to go" but mostly
because I sometimes have to work with web designers (graphical
artists) who I can't bother to modify my Lisp code directly. It turned
out that I use it very rarely - I think it's clumsy. I usually use
CL-WHO.

I personally think that "separation of logic and presentation" is a
good idea in theory but it rarely works in practice, unfortunately.

Cheers,
Edi.