Re: Could it be possible to support configuring with *.cfg instead of *.zcml?

On 11/24/13, 3:58 AM, Asko Soukka wrote:
> Hi Robert,
>
> Thanks for your comments.
>
> Robert Niederreiter wrote:
>> Nested directives is definitely a showstopper here, using cfg files
>> would imply to implement a semantic hack in order to achieve nested
>> directives or skip them at all. Both is not desireable.
> Agreed. So, the technical issues against cfg:
>
> - requirement for unique section headers
> - cannot support nested directives
>
> Where nested directives are still required in Plone context? I remember
> seeing only <class><require/></class> (and in many cases there would
> have been less lines with a single directive).
>
>> As alternative to cfg files YAML might be discussed, which actually
>> looks prettier than XML and can be used to describe nested structures.
> I also thought about YAML, but I'm not sure how widely it's adopted
> elsewhere within Python developers. Also, it would be a completely new
> syntax in Plone stack.
>
>> Anyway, i fear that there's not that big interest in changing or
>> extending the way ZCA registration works at all, as grok showed people
>> are basically fine with using ZCML (even if they're not big XML
>> enthusiasts) and prefer the use of not-so-loved syntax over another
>> package adding complexity and thus possible confusion.
> True.
>
> We have to teach a couple of new Plone developers every year.
> Grok-approach has been easier for them to become productive, but sooner
> or later there is the infamous Z-curve in learning. This time where grok
> does not work and you still have to learn zcml. Next year I've thinking
> about teaching zcml first, again...
>
> That's why I'm thinking about extending zope.configuration instead of
> inventing something completely new (like grok was). That way it should
> be easier to reach feature parity with zcml (because all the same
> directives are used).
>
> Maybe zope.configuration could be extended to use venusian.scan to
> register directives, when there is configure.py in your package..
>
A month ago I experimented with some code to automatically translate 
ZCML into Python-based configuration, using an AST-based approach 
similar to Chameleon. The result for Plone 4.3: 
https://gist.github.com/davisagli/7047450

I'm not seriously proposing pursuing this as a change in configuration 
style. My motivation was to see whether caching and executing Python 
bytecode could lead to improved performance for startup compared to 
parsing XML. Unfortunately there wasn't a big improvement; most of the 
startup time is spent importing and executing modules.

Someone should check over that gist, though, and make sure we aren't 
accidentally configuring a bunch of things we don't use.

I agree with others that it's almost impossible to introduce a new style 
of configuration in a way that actually makes things simpler.

If you have any use or interest in the zcml2py translation code I can 
post it, but it'll take a bit of cleanup first as it's currently spread 
through several places.

David


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