class Options:

instance = None

def __init__(self,options):

self.options = options

@classmethod

def set(cls,options):

"""Create an Options instance with the provided dictionary of

options"""

cls.instance = Options(options)

@classmethod

def inst(cls):

"""Get the Options instance.

"""

if cls.instance is None:

raise OptionsError("No options have been set")

return cls.instance

@classmethod

def get(cls,name,as_type = str):

"""Get an option by name.

Raises an OptionsError if the option doesn't exist.

"""

inst = cls.inst()

if name in inst.options:

return as_type(inst.options[name])

else:

raise OptionsError("No option with key '%s'" % name)

@classmethod

def overwrite(cls,name,value):

inst = cls.inst()

inst.options[name] = value

@classmethod

def isset(cls,name):

"""Checks whether the option exists and is set.

By set, it means whether the option has length. All the option

values are strings.

"""

inst = cls.inst()

if name in inst.options and \

len(inst.options[name]) > 0:

return True

else:

return False

class OptionsError(Exception):

pass