On 4 March 2014 15:22, <exarkun@twistedmatrix.com> wrote:
The big downside of a "configuration object" is that "configuration" isn't any kind of abstraction. "Configuration" approximately means "stuff". Where does your "configuration" end? By just saying this is where "configuration" goes you've defined its scope as infinite. Before you know it, there's 80,000 items in your "configuration" object and you're really much worse off than if you'd just added a couple more arguments to `__init__`.
Agree.
I'd like to see this discussion going in the other direction so to give it a little push that way, here's a specific suggestion. :) Most or all of this may be recycled from discussion that's already taken place - I'm not taking credit, just repeating it. :)
Give `Request.__init__` some new optional arguments to control the size of the header. This could be several arguments like `maxHeaderLines` and `maxHeaderValueLength` and so on... Or perhaps it should just be one argument that can completely describe the header size limitation (stretching this idea further, perhaps the one argument is a callable that takes a `Headers` instance and determines if it has gotten to big).
Then, perhaps, also give `HTTPFactory.__init__` (and therefore `Site.__init__` a `requestFactory` argument so that the request class can be replaced more easily (although setting the `requestFactory` attribute after creating an instance isn't *too* bad).
Why setting `requestFactory` attribute after instanciation isn't too bad? Why not apply the same rule for setting attributes like maxHeaders and maxHeader size in Request itself?
These two things combined make the usage pretty flexible while still being pretty simple and without involving any more complicated "configuration" system:
def requestFactory(*args, **kwargs): kwargs["headerSizeLimit"] = HeaderSizeLimit( maxLines=23, maxTotalBytes=57, ...) return Site.requestFactory(*args, **kwargs)
site = Site(..., requestFactory=requestFactory)
The HeaderSizeLimit class looks like a Configuration class and I am happy with it. I will go and update the branches to include suggested changes. Thank you all for the feedback!
If anyone is really interested in building (or adopting) a more general "configuration" system for Twisted then I suggest you start by looking up some of Twisted's past attempts including the the "Coil" library Itamar started (he'll have to provide a link, I've lost track of where it lives now).
I am not really interested in building a big "configuration" system for Twisted so don't worry for the link. Thanks! -- Adi Roiban