[Product-Developers] Re: [Plone-developers] plone.app.layout ViewletBase and portal_url

Wichert Akkerman wichert at wiggy.net
Sat Mar 8 13:20:05 UTC 2008

Previously Martin Aspeli wrote:
> Wichert Akkerman wrote:
> > I'm debugging some code that broke in a very unexpected way:
> > 
> > (Pdb) p getToolByName(self, 'portal_url')
> > 'http://localhost:8080/Plone'
> > 
> > That should return a tool, not a string. This turned out to be caused by 
> > plone.app.layout.viewlets.common.ViewletBase.update which sets 
> > self.portal_url to the portal URL. This looks harmless, but due to 
> > acquisition this will break patterns like this:
> > 
> > class MyViewlet(ViewletBase):
> >    def update(self):
> >       super(MyViewlet, self).update()
> >       self.mt=getToolByName(self.context, "portal_membership")
> >       self.somemethod()
> > 
> >    def somemethod(self):
> >       return self.mt.ToolMethod()
> > 
> > the problem here is that in somemethod() self.mt gets acquisition wrapped in 
> > the viewlet, so when ToolMethod does getToolByName(self, "portal_url") it
> > finds the portal_url variable ViewletBase.update set on the viewlet instead
> > of the tool.
> Ouch!
> This is precisely the reason that I *always* do (and advocate):
>      context = aq_inner(self.context)
> at the top of any method in a view or viewlet, and then use the 
> 'context' variable throughout the method instead of self.context.

That would still have broken: self.mt will give you the membership tool
wrapped in the view, so a getToolByName call inside the membership tool
would get the wrong result.

> > I would like to rename that variable in ViewletBase to prevent this problem 
> > but I do not have a good overview of how many people are relying on that 
> > specific variable to be set. If you are relying on this please let me know 
> > ASAP. If I here no objection I intend to rename the variable for the 
> > upcoming Plone 3.1 alpha release.
> I'm not sure we can do this. It's used in templates (view/portal_url) 
> that are likely to have been customised in several places. :-/

Hmm. Perhaps we can add a zope.deprecate wrapped portal_url in
ViewletBase to warn people?


Wichert Akkerman <wichert at wiggy.net>    It is simple to make things.
http://www.wiggy.net/                   It is hard to make things simple.

More information about the Product-Developers mailing list