Using viewlets (and views) in third-party products

Martin Aspeli optilude at
Mon Aug 27 11:52:24 UTC 2007

Wichert Akkerman wrote:
> Previously Martin Aspeli wrote:
>> Wichert Akkerman wrote:
>>> Perhaps it can more generic. Basically both are instances of a 'only 
>>> apply X when condition Y is satisfied'. Y in this case is either a 
>>> specific skin being selected or a product being installed. Would it be 
>>> possible to have a generic 'only use if feature X is here' framework in 
>>> place? That could be added to plone.theme instead of creating another 
>>> package that hooks into the same places as well.
>> Is that an endorsement for having a generalisation of this in 
>> plone.theme, and having that included in 3.0.x rather than 3.5?
> No, but it is an endorsement for a 2.0 version of plone.theme which
> supports that. People who need it can then use that instead of the
> plone.theme that is shipped with Plone 3.0.

There is a slight problem here, in that plone.recipe.plone (currently) 
uses == type dependencies for all the eggs, to make sure we get a "known 
good" distribution of Plone, including all dependencies. This is because 
setuptools/buildout is a bit trigger happy with upgrades and we 
typically depend on all Plone packages being released simultaneously.

In fact, you *can* override, by passing an 'eggs' parameter to 
plone.recipe.plone, but I'm not sure what would happen if a product's depends on a newer version of a core plone package.

>> Finally, we need to be cognizant of performance: this runs on each request.
> That's a reason for not using yet-another pre-traversal hook.


Acquisition is a jealous mistress

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