[Zope3-dev] Re: The elevator speech for Zope 3

[David Pratt]

Hi Philipp. I am strongly attached to packages and software that is 
reusable in and out of zope 3. Explicitly defining configuration using 
decorators should keep configuration top of mind (which is where I want 
to keep it when I develop) and not interfere with reuse goals. Further, 
I don't have to write or format xml at all since all interaction with it 
would be python.

I believe I understand where you are going with Grok development quite 
well. At the same time, I recognize another approach for dealing with 
the labor of component registration that could assist the zope 3 
developer. Obviously this is not relying on a Grokker for its 
configuration magic since you need to be explicit, but this is how I 
wish to keep things.

Buildout is a wonderful tool and extending to the class level to write 
the xml text that zope needs seems natural for me. I use buildout as my 
setup and configuration automation tool for virtually everything from 
physical server setup to configuring and building just about all the 
software I use at the present time. I don't see it as the wrong place to 
automate this task and to save time. Frankly, there is irony in my 
configuring software in other languages using buildout but not my own 
python packages in zope 3 to the level of the class.

Regards,
David


Philipp von Weitershausen wrote:
> On 8 Oct 2007, at 15:14 , David Pratt wrote:
>> Hi Uwe. I have been thinking of something similar and posted on the 
>> list a couple of weeks back:
>>
>> http://mail.zope.org/pipermail/zope3-dev/2007-September/023653.html
>>
>> I want the zcml to be generated with a switch on zc.buildout so all 
>> configuration is auto generated. Currently site.zcml is done this way 
>> and I want to extend this to the class level. Recipe's would be 
>> produced  to handle different types of configuration by providing the 
>> decorator methods.
>>
>> I'm hoping to use decorators exclusively on the classes to do this so 
>> there would be no need to modify the code in the classes themselves to 
>> accomplish the configuration.  Further, classes without this 
>> decoration would be skipped by the process allowing this approach to 
>> be incorporated into your code gradually. I want to be able to see and 
>> verify the zcml produced and have the same control over it that I have 
>> now.
> 
> We were considering the generation of ZCML briefly when developing Grok, 
> but discarded it quickly. The ZCML machinery (zope.configuration) itself 
> is nice, but many of the directive handlers that are out there are 
> flawed. In particular, the browser:page handler is so awful, I'm very 
> very happy not having to use it in Grok. Death to magic class creation! 
> Other handlers have side-effects during parsing time (as opposed to 
> action execution time). Of course, we could've always written our own 
> directives, but that wasn't the exercise.
> 
> Soon, we will change Grok so that it emits configuration actions, rather 
> than doing the registrations right away. That way, you will still be 
> able to inspect what exactly Grok is doing (for example by dumping all 
> configuration actions before or instead of executing them), but you 
> won't have to deal with ZCML anymore. You will also be able to use the 
> overrides mechanism with them.
> 
>> The advantage of having it in buildout is that it becomes integrated 
>> into the development of the application, which is by nature just the 
>> configuration glue for your packages.
> 
> I think buildout is entirely the wrong place to do this, but feel free 
> to pursue your own ideas :).
> 
>