[Zope3-dev] zope.etree comments

[Martijn Faassen]

Hi there,

I just noticed the existence of zope.etree. Besides a minor comment on 
its use of 'zope' as the namespace package, which I believe is generally 
reserved for core components, I have the following more conceptual comment:

There are currently three implementations of the ElementTree API:

ElementTree  (original implementation in plain Python)
cElementTree (same API, faster, C-code)
lxml.etree   (same API but vastly extended, faster, dependency on 
libxml2 etc)

The motivation of zope.etree appears to be to be able to swap out 
ElementTree with lxml for performance reasons. While as the developer of 
lxml the increased use of lxml makes me happy, I still wonder why this 
choice was made. Glancing through the code I cannot find a reference to 
cElementTree at all. I wonder why the choice wasn't made to simply swap 
out with cElementTree instead?

After all, the reason to do this, as stated, is performance. 
cElementTree has performance, is easier to install than lxml (as it 
doesn't have dependencies), will ship with Python 2.5, and has the same 
API as ElementTree itself.

The main reason to use lxml over cElementTree is not performance 
(sometimes it's faster, sometimes slower, depending on what you do) but 
is extended features - lxml has a huge featureset. Some of these 
features can of course also help with performance, but only if you use 
them.

More features cannot be the reason for zope.etree however, as the whole 
point is to use lxml and ElementTree interchangably, right?

Regards,

Martijn