On IRC Fred asked:
> Why are delimiters and comment_prefixes in the constructor signatures?

Like most configurable options, they were added to the initializer one by one (after `allow_no_value`). Only later did I notice that actually things like optionxform, _boolean_states, etc. are configurable by assignment. So this is a design decision whether one way should be preferred over the other. In a way that's unfortunate that we now have two obvious ways to do it.

I believe that keyword arguments are far better because they are more declarative, e.g.:

parser = SafeConfigParser(delimiters=(':=',),
                          comment_prefixes=('//',))

vs.

parser = SafeConfigParser()
parser._delimiters = (':=',)
parser._comment_prefixes = ('//',)

It's the way ORMs and many other frameworks do it and it feels natural.