[Zope3-dev] what is ZCML?

[Jean-Marc Orliaguet]

Jim Fulton wrote:

>
> Yup.
>
> BTW, a general thing to keep in mind:
>
> - Indirection and abstraction are inherently bad because they
>   hide things. :)
>   (This is a corolary of "explicit is better than implicit".)
>
> - But indirection and abstraction can provide benefits that outweight
>   their inherent bad-ness.
>
> Whenever we consider ptoviding a high-level/automated facility, we have
> to weigh the benefit against the inherient badness.
> [...]
>
> Jim
>

yes, except that ZCML adds strictly no abstraction compared to what 
would have been written in python. It only "paraphrases" python by 
hiding lines of code. When I look at a zcml directive I often have to 
read that handler's code to see what it actually does and I have to find 
the objects, classes in files, .. that it handles.

that's 2 indirections, but no abstraction

Abstraction would in the case of ZCML mean that paths to python modules 
and classes would be hidden, that objects (adapters, pages, menus) could 
be given a shorter name that I could use inside ZCML for configuration 
purposes without registering these names in zope, it would mean that I 
could group directives together in a set and apply rules to it without 
always refering to the location of each individual object on the 
filesystem, that I wouln't have to do a grep on all zcml files when I 
move or rename files (I would register paths only once) ... It would 
mean that I could register all images inside a folder without listing 
them all one by one.

This would be the beginning of something called 'abstraction', but 
that's still far away from it :-).

best
/JM