[Zope3-dev] Clarity, ClearSilver integration for Zope 3

[Martijn Faassen]

Hi there,

I've just checked in a new package into the Zope 3 base called Clarity. 
What it does is integrate ClearSilver templating into Zope 3 (trunk, 
though I expect Zope X3.0 or even Five support should be easy enough). 
It's all still rough, but initial tests show ClearSilver templates can 
be quite a bit faster than ZPT, and they have other possible benefits. 
In my simplistic experiments I got transaction rates about 2 to 5 times 
higher than you can reach with ZPT, testing this with the 'siege' utility.

Here's an extract from the README that describes the motivation for this 
experiment.

Why?
---

Zope 3 already has page template and even DTML, why would I want to
use this? Some possible benefits ClearSilver brings are:

* Absolute separation of logic from template. You cannot do
   complicated logic in a ClearSilver template, you can only extract
   data. You cannot call into the Zope 3 API *at all*.

* Increased debuggability. Calling APIs is impossible from the
   template, which means that most bugs the API should appear in Python
   code already, where the programmer can worry about them, not the
   person who is tweaking the templates. While you are building a
   template you will *never* be bothered by, say,
   ComponentLookupErrors.

* Increased testability. Since you know what HDF structure you expect
   to get in advance, you can test this using a normal unit test from
   Python code. Your template can stay simple.

* Performance. Admittedly simplistic testing with 'siege' shows that
   for larger templates, ClearSilver templates integrated into Zope run
   several times faster than the equivalent ZPT page.

However, since no significant codebases exist that use this facility,
these benefits are somewhat speculative.

More about ClearSilver here:

http://www.clearsilver.net

You can check out Clarity from the Zope 3 base, here:

http://codespeak.net/svn/z3/clarity/trunk/

Have fun!

Regards,

Martijn