[z3-five] context-based utility lookup

[Chris Withers]

Philipp von Weitershausen wrote:
>> Indeed, but can you override the context that gets used to figure out 
>> what utility gets picked up?
> 
> Yes, you can always pass in a context explicitly in which case the 
> closest site to that context will be used for the lookup.

Good stuff :-)

Out of curiosity, is it acquisition or __parent__ that's used to find 
the "closest" site?

> Actually, the publication is quite agnostic of sites, fortunately. All 
> the publication does is send out an IBeforeTraverseEvent for each object 
> it is about to traverse. zope.app.component has a subscriber for that 
> event on ISites that "remembers" the site in a thread local.

Hmm, that brings me to another minor bug bear: I hadto step through the 
event process a week or so ago in pdb and was pretty horrified as to how 
many function calls were involved from the time event.notify() got 
called to when my event subscriber code was actually called. Not only 
does it make pdb'ing a pain, but I also wonder how much of a performance 
hurt that's going to be in a high volume application with a lot of 
events being fired?

cheers,

Chris

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