[Grok-dev] Grok and chameleon

[Martijn Faassen]

Hi there,

Sebastian Ware wrote:
> I have a quite a few running apps that use lots of TALES expressions,  
> this would have a major impact. I've looked at it before and found it  
> was a pain for me, I'll look again and let you know. Other than that,  
> if there is a measurable performance gain and it doesn't mess up i18n,  
> I am all for it.

We need to provide a way so that people with existing applications can 
provide forward, either by supporting zope.pagetemplate as a backwards 
compatibility mode, or by supporting TALES expressions by default in 
Chameleon (as a mode. the default wouldn't).

I think performance is only one reason to shift to Chameleon.

I'm more thinking about features, myself. The default use of 'python:' 
for all expressions is something I've wanted for a long time. It makes 
Grok easier to explain. It also makes it simpler to reason about the 
code, as one doesn't have to worry about the internals of the whole path 
expression engine anymore. It also offers tuple unpacking,  and 
Genshi-style interpolation syntax:

http://chameleon.repoze.org/docs/latest/zpt.html#extensions

I'll also note that actually moving away from TALES expressions to 
Python expressions is by itself a (minor) performance gain all by itself.

Regards,

Martijn