[Twisted-Python] Configuration options for twisted code

[Adi Roiban]

> A configuration system would take a while to design

This reads like: A configuration system will never be implemented.

I agree that for the time being we can implement current tickets using
__init__ arguments,
but why not try to implement something simple?

Example:

TWISTED_WEB_DEFAULT_CONFIGURATIO = {
  'request.headers.count': 500,
  'request.headers.size': 16384,
  'request.session.name' :  'TWISTED_SESSION',
  }

# We can have a helper method to get default configuration
configInstance = TWISTED_WEB_DEFAULT_CONFIGURATION.copy()
configInstance[''request.headers.count'] = 100
t.w.s.Site(configuration=configInstance)

Or a bit more structured:

class RequestConfiguration(object):
   def __init__(self):
     self.max_headers_count = 500
     self.request_max_header_size = 16384
     self.session_cookie_name = 'TWISTED_SESSION'
     self.session_cookie_secure = True
     self.session_cookie_http_only = True

class TwistedWebConfiguration(object):
  def __init__(self):
       self.request = RequestConfiguration()

configInstance = TwistedWebConfiguration()
configInstance.request.max_headers_count = 100

t.w.s.Site(configuration=configInstance)

Or a mix:

configInstance = TwistedWebConfiguration()
configInstance.set('request.headers.count', 100)
t.w.s.Site(configuration=configInstance)

and support some sort of inheritance.

configInstance.set('timeout', 100)
assert configInstance.get('request.timeout') == 100
configInstance.set('request.timeout', 200)
assert configInstance.get('request.timeout') == 200

Or some design used in other project... or some other crazy idea.

-----

In Twisted web I found both configuration overridden in sub-classes
(t.w.s.Site) and defined via __init__ (t.w.s.File)

twisted.web.static.File has 5 arguments, but the following
configuration are missing : indexNames, childNotFoundResource,
forbiddenResource, directoryListing resource

As Jean-Paul commented, when there are too many arguments and they are
all related, they could be represented by a single argument.
For me, this single argument could be a configuration object.

Too many arguments are a code smell, but when you can say that a
method has too many arguments?

Thanks!
-- 
Adi Roiban