First of all. Thanx for the help!!! The internet is just fantastic!! I like the wrapper approach. I had not thought of that approach myself. Sounds very reasonable. -So I started wrapping Resolver, but got stuck pretty fast. I get a problem saying that 'NoneType' object has no attribute 'addCallback' "addCallback" seems to be implemented in defer.py, but im unsure on how to handle that in the wrapper? Kind regards /Tax P.S: As a side question: In my old hack approach, which I have had almost working, I have had problems constructing valid DNS answers. Wold you happen to know what requirements there is to the returning package, to be accepted. I made some attempts by using pickle to capture live packages, but have a hard time tweaking other values than the address. Ideally I would like to pass on a very short TTL, so the client would not be bothered by fake DNS when I turn the system off. As you might have guessed, Im building a gateway system for a small set of apartments. Requirements are: invalid domains should go to a shop valid domains should be redirected to the shop if the client have not paid, except if the query is for paypal. 2009/10/25 <exarkun@twistedmatrix.com>
On 24 Oct, 08:04 pm, jesper@taxboel.dk wrote:
Im looking at the common.py and I feel a bit confused about how to wrap a resolver.
Would'nt a subclass achieve the same thing. I would only need to implement the changed functions in the subclass.
I guess my problem is that I dont exactly know how to write a wrapper in python.
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.
Jean-Paul
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