[Product-Developers] RFC: Venusian-based Python-syntax alternative for ZCML-configuration

[Asko Soukka]

Hi,

last year there was (again) a long discussion about pros and cons of 
grok-based configuration:

http://plone.293351.n2.nabble.com/GROK-RULES-I-WANT-IT-MORE-Was-The-grokless-madness-and-unable-to-create-a-simple-form-tt7564217.html

TL;DR; It seems that Grok will never have feature parity with ZCML, but 
it has use cases and we have nothing to replace it.


I've been experimenting with an alternative lately: a venusian-based 
configuration library for zope.configuration; All python, minimal 
dependencies, uses the same directive code as ZCML (= feature parity), 
no conventions - just IDE-friendly Python-based configuration.

I'm not forcing this to anyone. An another way to configure may be the 
last thing we need. Yet, I want to try this approach as a 
grok-replacement for our (my employer) internal packages during this 
spring (we'll have new developers and grok has always been easier to 
teach than ZCML). Only for add-on-packages.

So, before spending too much time polishing the code, I'd like to 
request for your comments about the configuration syntax, which I've 
been tinkering:

https://github.com/datakurre/collective.venusianconfig/blob/master/demo/src/venusianconfigdemo/configure.py

https://github.com/datakurre/collective.venusianconfig/blob/master/demo/src/venusianconfigdemo/views.py

https://github.com/datakurre/collective.venusianconfig/blob/master/demo/src/venusianconfigdemo/adapters.py

https://github.com/datakurre/collective.venusianconfig/blob/master/demo/src/venusianconfigdemo/portlets/configure.py


So, it's not grok. It's a Python-syntax for zope.configuration with 
optional support for limited set of decorators (directives with class, 
factory or handler).

Venusian-library is used to make all configuration directives lazy: 
venusian creates "registration callbacks" during module import, but 
those callbacks are only executed when packages is imported by 
zope.configuration.


The current catch is that this needs one line in zope.conf (for 
monkeypatching zope.configuration) and custom site.zcml (for 
z3c.autoinclude also Python-configured packages). These are required to 
work around hardcoded zcml-expectations.


Waiting for your comments.

Regards,
Asko