[Twisted-Python] Handeling unresolved DNS queries?

exarkun at twistedmatrix.com exarkun at twistedmatrix.com
Sun Oct 25 12:47:32 EDT 2009

On 24 Oct, 08:04 pm, jesper at taxboel.dk wrote:
>Im looking at the common.py and I feel a bit confused about how to wrap 
>Would'nt a subclass achieve the same thing. I would only need to 
>the changed functions in the subclass.
>I guess my problem is that I dont exactly know how to write a wrapper 

There's nothing special to it.  Just do the obvious thing:

    class SomeWrapper:
        def __init__(self, wrapee):
            self.wrapee = wrapee

        def someMethod(self, args):
            do something with self.wrapee.someMethod and args

common.py will show you all the methods that a resolver is expected to 
have.  Subclassing ResolverBase might help, though it's unfortunate that 
it works by demultiplexing everything to "_lookup", a private method 
that Twisted's compatibility policy doesn't guarantee will continue to 
operate as it presently does.

Wrapping (ie "containment" or "has-a") is just an alternative 
implementation strategy to subclassing (ie "inheritance" or "is-a"). 
Generally it's a better approach for various reasons, none of which are 
really specific to Twisted.


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