Re: [Perl-widget-developer] XSP PerForm taglib (fwd)

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My initial reaction is that I think this is much more complex than a widget 
library that produces HTML and it's even less clear to me that XML is a 
good delivery mechanism for abstracting forms.

I truly believe that when you make an app into an HTML app vs a WML app vs 
anything else that the screens are significantly different.

I think that this XML stuff may be fine for content sites like newspapers, 
but for an app it seems like it's a lot of work for much less gain than you 
get on the pure content management side.

Later,
    Gunther

At 10:49 PM 6/8/2001 +0100, Matt Sergeant wrote:
>Thought this might interest some of you widget geeks :-)
>
>--
><Matt/>
>
>     /||    ** Founder and CTO  **  **   http://axkit.com/     **
>    //||    **  AxKit.com Ltd   **  ** XML Application Serving **
>   // ||    ** http://axkit.org **  ** XSLT, XPathScript, XSP  **
>  // \\| // ** mod_perl news and resources: http://take23.org  **
>      \\//
>      //\\
>     //  \\
>
>---------- Forwarded message ----------
>Date: Fri, 8 Jun 2001 22:40:56 +0100 (BST)
>From: Matt Sergeant <ma...@se...>
>To: AxKit Users Mailing List <axk...@ax...>
>Subject: XSP PerForm taglib
>
>Taking a bunch of ideas from a number of places I've started putting
>together what I call the "PerForm" taglib. This is sort of a magic form
>tag library that will enable you to write web forms sucking data from
>various sources more easily.
>
>I'm looking for some sort of feedback on this, though it's pretty funky as
>it stands IMHO.
>
>Best way to describe it is with an example (this assumes passing
>familiarity with XSP):
>
>===============
>
><?xml version="1.0"?>
><xsp:page
>     xmlns:xsp="http://apache.org/xsp/core/v1"
>     xmlns:web="http://axkit.org/NS/xsp/webutils/v1"
>     xmlns:f="http://axkit.org/NS/xsp/perform/v1"
>     language="perl"
>     indent-result="yes"
> >
><!-- TOP LEVEL LOGIC -->
><xsp:logic>
>
># Each function recieves a $ctxt object, which is a hash to
># store things in. It has one entry by default, "Form", which
># is a hash of form values
>
>sub load_title {
>     my ($ctxt, $default, $current) = @_;
>     warn("load_title ($default, $current)\n");
>     return $current || $default;
>}
>
>sub load_link {
>     my ($ctxt, $default, $current) = @_;
>     warn("load_link ($default, $current)\n");
>     return $current || $default;
>}
>
>sub save_title {
>     my ($ctxt, $new_value) = @_;
>     warn("save_title : $new_value\n");
>}
>
>sub save_link {
>     my ($ctxt, $new_value) = @_;
>     warn("save_link : $new_value\n");
>}
>
>sub start_form_create {
>     my ($ctxt, $save_mode) = @_;
>     warn("start_form\n");
>}
>
>sub end_form_create {
>     my ($ctxt, $save_mode) = @_;
>     warn("end_form\n");
>     # if everything is OK, and we're in save_mode, redirect.
>     if ($save_mode) {
>        if ($ctxt->{OK}) {
>          # note mixing taglibs and Perl!!!
>          <web:redirect uri="everything_ok.xsp"/>
>        }
>     }
>}
>
></xsp:logic>
>
>Title:
>Link:
></xsp:page>
>
>===============
>
>OK, hopefully that hasn't confused anyone too much. Now the idea is that
>these forms always get submitted back to themselves. They do their own
>validation. If everything went well and the form got saved OK, they issue
>a redirect to another page. It's kinda like the MVC model, only slightly
>spiced the AxKit way :-)
>
>Now when the form is first loaded, the input fields are populated by a
>callback to the load_<name>() function, where <name> is the name entry of
>the particular form field. So to populate the first textfield, it calls
>load_title(...). It passes in parameters $ctxt, $default, and $current.
>Note that $current will only be filled if this form has already been
>submitted once (filled with the current value, obviously). The value you
>return is what goes in the text box that the user sees.
>
>When the form is submitted, the save_<name>() functions are called. This
>time they are passed the $ctxt and the new value. There you can do
>validation or whatever you like (save to a DB, etc).
>
>Each view of the form is started by a call to start_form_<name>(), where
><name> this time is the name attribute on the form. When all the form's
>callbacks have been performed, the end_form_<name>() callback is called.
>
>The $ctxt object is a simple hashref that you can fill with whatever you
>like. It's there to help you maintain state between the callbacks. It
>contains one entry by default, "Form", which is a hashref to all the other
>form values. This allows you to do validation where one value depends on
>another.
>
>If you *don't* want to supply callbacks for load_*, then it defaults to
>using either the current value (i.e. the value last posted to the form),
>or the default value specified if this is the first load of this form.
>
>Now when all this has been done, it doesn't generate a HTML widget. It
>just generates some XML decorated with all the relevant attributes. You
>need to write an XSLT stylesheet (which I'll include with the package for
>HTML) to render it to HTML. But it's really simple to do that with
>xsl:include/xsl:import. I may even be persuaded to do an XPathScript
>stylesheet for it :-)
>
>I welcome your feedback on this. I think it will make building complex
>forms really easy. One nice thing with XML is we can put all that nasty
>callbacks code in another file, and use entities to load it in. Or we can
>use "use OtherPackage qw(...)" to import the functions to the current
>namespace. Either way will work.
>
>I can put this in CVS if people want to play with it as it stands. But I
>have only implemented the textfield widget as yet.
>
>--
><Matt/>
>
>     /||    ** Founder and CTO  **  **   http://axkit.com/     **
>    //||    **  AxKit.com Ltd   **  ** XML Application Serving **
>   // ||    ** http://axkit.org **  ** XSLT, XPathScript, XSP  **
>  // \\| // ** mod_perl news and resources: http://take23.org  **
>      \\//
>      //\\
>     //  \\
>
>
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__________________________________________________
Gunther Birznieks (gun...@eX...)
eXtropia - The Open Web Technology Company
http://www.eXtropia.com/