[z3-five] context-based utility lookup

[Chris Withers]

Philipp von Weitershausen wrote:
>> Do you see that as a good or a bad thing?
> 
> The yes was for the "really". If you don't believe me, read the chapter 
> on Sites in my book. It's all explained in detail there.

Ah, okay, haven't got to that section in the 2nd Ed yet ;-)

> IMO not having to specify a context is a good thing. Sometimes code 
> doesnt' have access to a context, but it still wants to lookup a 
> utility. Should it not be possible to let that utility come from a local 
> component registry? I as the one who makes up application policy should 
> be able to say where that utility comes from.

Indeed, but can you override the context that gets used to figure out 
what utility gets picked up?

>> Well, I'd imagine if you went to the trouble of registering local 
>> utilities, you did so for a reason?
> 
> You're missing the point. The code that's looking up the utility might 
> be some completely different piece of software than the piece of code 
> that provides the utility. 

No, I understand that.

>> If that's the case, then how do I make sure the right utilities are 
>> used when I'm traversing around several objects in different locations 
>> in the same piece of code?
> 
> There's only one kind of traversal -- URL traversal -- and it only 
> happens once per request.

Ah, okay. I suspect I'm going to learn lots more about this when I come 
to refactoring the publications stuff...

> The other thing sometimes referred to as 
> "traversal" is resolving object graphs. That doesnt' trigger the site 
> remembering code.

Good ;-)

cheers,

Chris

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