From: Avi Bryant <avi@...4.com>
Date: 2001-03-23T15:56:48+09:00
Subject: [ruby-talk:13120] Re: ZPT, a next-generation template technology (repost)


I can't help but to point out that we already have an implementation of
this concept in Ruby (although I'm pleased to see the idea finally
showing up somewhere else).

http://beta4.com/iowa

On Fri, 23 Mar 2001, Conrad Schneiker wrote:

> FYI. Thought some Rubies might be interested in this.
> 
> Subject: ZPT, a next-generation template technology
> Date: Sat, 17 Mar 2001 01:43:50 -0000
> From: "Hamish Lawson" <hamish_lawson@btinternet.com>
> Newsgroups: alt.php, comp.lang.java, comp.lang.perl.misc, comp.lang.python
> 
> Hamish Lawson wrote:
> > 
> > The Zope Presentation Templates project is underway at Digital Creations
> > to develop a next-generation template technology for Zope* that is
> > XHTML-compliant and which makes it easier for designers to work with.
> > However it is hoped to design it in such a way that as much as possible
> > is not specific to Zope, in the belief that the technology is more
> > widely useful and could be adopted by other languages and tools.
> > Developers from other communities may want to consider contributing to
> > the design of ZPT to help keep it language-independent, and to consider
> > implementing the approach in their programming language of choice.
> > 
> > First of all some background on what is meant by "next-generation".
> > 
> > In the beginning programmers wrote program code with embedded HTML. Then
> > technologies like eperl, ASP, PHP and JSP allowed us to reverse this and
> > to embed program code in the HTML. However a school of thought wanted to
> > have greater separation of presentation and logic, and so various
> > template mechanisms were devised that provided just enough
> > programmability to control presentation, but which moved the business
> > logic out elsewhere. One example of this approach is Freemarker:
> > 
> >    <h1>$customername</h1>
> >     <table border="1">
> >         <tr>
> >             <td>Date</td>
> >             <td>Amount</td>
> >         </tr>
> >         <list deposits as deposit>
> >             <tr>
> >                 <td>${deposit.date}</td>
> >                 <td>${deposit.amount}</td>
> >             </tr>
> >         </list>
> >     </table>
> > 
> > Instead of custom tags some other template mechanisms use special
> > markers to designate control structures, but in general most template
> > mechanisms share the property that their templates are not compliant
> > with XHTML (though the rendered output may be). As such it can be
> > awkward trying to use such template mechanisms with authoring tools that
> > only understand XHTML.
> > 
> > The approach that the ZPT project is pursuing is to attach the control-
> > flow, formatting and placeholder directives as *attributes* of standard
> > XHTML tags. The example above thus becomes something like:
> > 
> >     <h1 zpt:insert="customername">Bob Smith</h1>
> >     <table border="1">
> >         <tr>
> >             <td>Date</td>
> >             <td>Amount</td>
> >         </tr>
> >         <tr zpt:repeat="deposit deposits">
> >             <td zpt:insert="deposit/date">01/02/2001</td>
> >             <td zpt:insert="deposit/amount">23.40</td>
> >         </tr>
> >     </table>
> > 
> > Because this doesn't make use of special tags, but employs attributes
> > instead, it should pass unscathed through most decent authoring tools.
> > Moreover (borrowing an idea from Enhydra's XMLC template scheme) the ZPT
> > template scheme allows typical sample content to be used as a proxy for
> > the real data (which is substituted by the template engine), so making
> > it easier to work with in an authoring tool.
> > 
> > More information on the rationale of attribute languages can be found
> > 
> >     http://dev.zope.org/Wikis/DevSite/Projects/ZPT/AttributeLanguage
> > 
> > An overview of ZPT can be found at
> > 
> >     http://www.zope.org/Wikis/DevSite/Projects/ZPT/VisionStatement
> > 
> > Hamish Lawson
> > 
> > * Zope is a leading open-source web application server and content-
> > management framework, written in Python by Digital Creations.
> 
> Conrad Schneiker
> (This note is unofficial and subject to improvement without notice.)
>