[Zope3-dev] Re: yagni on overrides?

[Martijn Faassen]

Hey,

Leonardo Rochael wrote:
[snip]
> So, perhaps, we don't need powerful zcml overrides, just cooperative package
> maintainers (of which we have plenty in this community).

Interesting to see some of my ideas for Grok make it back here. :) After 
your mail I realize now that with ZCML you can do more or less what I 
describe out of the box: you can simply supply multiple configuration 
files per package and tell people which one to include in their own 
package. That is definitely an interesting approach, so thanks for 
pointing that out, Leonardo.

Note that I think overrides/selective disabling is still useful in 
special use cases. It may be that you're in a hurry and just want to use 
the package out of the box, it doesn't have the ZCML you want. Just 
being able to disable or override little bits might be useful then.

Then again, I think you're arguing you should in that case simply copy 
the ZCML from the given package and eventually donate back your 
refactored version which does what you want. That makes sense.

In general, selective overrides and disabling tends to make more sense 
if you want to use 99% of a package's ZCML and only want to override a 
little bit to make progress. A form of grouping of different ZCML 
configurations indeed would be nicer in the other cases.

I also think overrides might be of use if you use package A which uses 
package B which uses package C, and you want to override something in 
package *C*. Of course with clever refactoring of individual 
configuration files in all three packages you could still pull that off, 
but it'd take a lot of communication.

A nice aspect of grouping configurations as a response to the desire to 
override/disable bits is that such groups can become part of the common 
code base and evolve.

Regards,

Martijn