[TransWarp] Template parsing and XML/HTML processing design

[Phillip J. Eby]

At 01:42 PM 7/21/03 +0200, Roché Compaan wrote:

>I really think this is a step backwards as far as templating
>technologies goes. Jean already mentioned the lack of a separate
>namespace for special attributes.

There is one, I just didn't use it in the example.  See my last message.


>Additionally I think to enforce
>the separation of ui and code to death is extreme. Some logic is
>legitimate in templating, specifically simple expressions that serves
>only the presentation. Off course you can go overboard with ZPT's
>"python:" expressions but PEAK does not need to make that available on
>the context if it is strongly against python expressions in the
>template.

PWT is intended to support reusable components or "widgets".  Embedding 
code in a template is like writing code to draw every dialog box in a GUI 
application pixel by pixel.  If every time you need something complex, you 
need to create a view component, you will enormously magnify your chances 
of being able to reuse the component in future applications.

So, although PWT will start out "behind" other templating systems in 
productivity, I expect its productivity level to be able to keep on 
climbing as widgets are developed.  I also know that for many applications 
I'll want to be able to make app-specific custom widgets, as subclasses of 
standard form widgets and such.  This sort of thing is very hard to do well 
with code embedded in the pages, regardless of whether it's Python or ZPT 
or DTML that's in the pages.


>I often find that it is too expensive to create a class or python script
>when I build templates and simple "python:" expressions are very useful
>then.

If you're using a PWT, it'll be because you've bound it as a method in a 
class, so the class is also the obvious place to put any such expressions, 
perhaps as binding.Once() expressions.  And the class you've bound it in is 
probably a Location wrapper, so you can put all the view-specific code in 
it you want without getting in the way of the domain logic.