[Zope3-dev] Re: Idea: Failure to lookup adapters

[Philipp von Weitershausen]

Stephan Richter wrote:
> On Monday 15 January 2007 14:25, Sidnei da Silva wrote:
>>   'We've tried to look up an adapter for (ISomething, ITheOther) but
>> none was found'
>>   'Found an adapter for IFoo, which is a base class for the IBar
>> interface requested. No adapter has been found for the most-specific
>> interface IBar'
>>
>> Comments?
> 
> My major concern is speed here.

It's a bit early to have that concern, we haven't even come up with a 
strategy yet ;).

   "Premature optimization is the root of all evil" -- Donald E. Knuth

> Any debug handling will make the registry 
> slower; I am using adapters very heavily in my code and any slow-down of one 
> lookup would be multiplied many times.

There are certainly ways in Python to have debug code in an application 
that won't be run in production mode, e.g.:

   if __debug__:
       # do expensive logging call here, or whatever

Code like this won't be run with python -O (which is what you'd 
obviously use in production).

> I wonder whether a different approach could be taken. The APIDOC code does 
> already a registration analysis. Maybe we can use the registrations in a away 
> that they simulate the adapter registry. Thus you could provide APIDOC (via 
> the Web UI or Python) with a component or instance and it tells you how it 
> tries to look up the adapter. Clearly that would be much slower, but okay for 
> inspection.

Sounds good. I like the explainAdapter() suggestion.


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