Templating engine?

Paramjit Oberoi p_s_oberoi at hotmail.com
Tue Jun 22 16:59:54 CEST 2004


>> The second point above is why I don't understand your claim that the
>> separation of presentation logic and markup would be easier to maintain. 
> 
> I can work on the HTML using all my favourite standard HTML tools, and
> the code using all my favourite standard Python tools. I can deal with
> each half individually without having the other getting in my way and
> spoiling my view. I can hash around the HTML as much as I like with,
> at most, minimal breakage - the only stuff in the HTML to break is the
> name bindings that tie it to the Controller code, and those are
> quickly and easily replaced. The API is very small and simple. How I
> structure my code is not dictated by the structure of my template. The
> implementation can be as granular as you like, so should be easy to
> test and profile right down to the atomic level. I can hand the HTML
> half to one developer to take care of and the code half to another.

OK, pretty good arguments.  I see the point.  I guess I would see it more
strongly if my favourite tool for editing both HTML and python wasn't a
standard text editor <0.5 wink>.

>> By flexibility I meant flexibility in what you can do by modifying the
>> template alone (since presentation logic can be added to the template).
>> In the case of 'DOM-style' systems you may have to edit the template as
>> well as the presentation logic (which would mean modifying the
>> 'program', not just the template).
> 
> You're making a false distinction here. The template and the
> presentation logic are as much a part of the "program" as the business
> layer they sit on top of. Editing the template markup is modifying the
> application. Editing the template logic is modifying the program.

I think it is a very real distinction.  If you are a user of the
application, you don't want to have to maintain a private set of
modifications to it.  Also, the application might be installed in a
read-only location...  It might even be compiled, once all the python
compilers really take off.

> Now, if you believe that it's the templating system's job to impose
> and enforce a certain kind of architecture upon the developer - one
> that makes it impossible to mix presentation and business logic
> together - then you can certainly make that argument. The popularity

Not at all.  In fact, it's the HTMLTemplate-like systms that enforce the
separation of markup from all code.  With Cheetah you can have as little
or as much code in the template as you want---no separation of any kind is
enforced.  This lack of enforced separation of markup and code is really
convenient.

-param



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