Configuration over convention.

Classy configuration:

>>> from stage import Conf
>>> class defaults:
... class SMTP:
...     ENABLED = False
...     TO = ''
...     SUBJECT = ''
...     # mail server
...     HOST = ''
...     # from email address
...     FROM = ''
...     AUTH = None
...     TLS = None
... class HTTP:
...     ENABLED = False
...     # web server host
...     HOST = ''
...     # web url
...     URL = ''
...     # http method
...     METHOD = 'GET'
... class SYSLOG:
...     ENABLED = False
...     # syslog host
...     HOST = 'localhost'
...     # syslog port
...     PORT = 514
...     # syslog facility
...     FACILITY = 'LOG_USER'
>>> class required:
... class LOG:
...     NAME = 'root'
...     # log level
...     LEVEL = 30  # warning
...     # default log formats
...     DATE = '%a, %d %b %Y %H:%M:%S'
...     # log entry format
...     ENTRY = (
...         '%(levelname)-4s -- %(asctime)s -- %(name)s: %(message)s'
...         ' (%(module)s.%(funcName)s at %(lineno)s)'
...     )
... class STREAM:
...     ENABLED = True
...     # redirect STDOUT to the logger?
...     STDOUT = True
...     # sets log level STDOUT is displayed under
...     LEVEL = 30  # warning
... class ROTATE:
...     ENABLED = False
...     # log file path
...     PATH = ''
...     # number of backups to keep
...     BACKUPS = 1
...     # interval to backup log file
...     INTERVAL = 'h'
...     ENCODING = None
...     MODE = 'a'
...     SIZE = 0
>>> config = Conf(defaults, required).freeze()
>>> config.LOG.NAME
'root'
>>> config.LOG.LEVEL
30
>>> config.LOG.DATE
'%a, %d %b %Y %H:%M:%S'
>>> config.STREAM.ENABLED
True

Telepathic environment configuration:

>>> from stage import TwoDeep, Env, env
>>> required = TwoDeep()
>>> with required.LOG:
... required.NAME('root')
... required.LEVEL(30)  # warning
... required.DATE('%a, %d %b %Y %H:%M:%S')
... required.ENTRY(
...     '%(levelname)-4s -- %(asctime)s -- %(name)s: %(message)s (%(mo'
...     'dule)s.%(funcName)s at %(lineno)s)'
... )
>>> with required.STREAM:
... required.ENABLED(True)
... required.STDOUT(True)
... required.LEVEL(30)  # warning
>>> with required.ROTATE:
... required.ENABLED(False)
... required.PATH('')
... required.BACKUPS(1)
... required.INTERVAL('h')
... required.ENCODING(None)
... required.MODE('a')
... required.SIZE(0)
>>> defaults = TwoDeep()
>>> with defaults.SMTP:
... defaults.ENABLED(False)
... defaults.TO('')
... defaults.SUBJECT('')
... defaults.HOST('')
... defaults.FROM('')
... defaults.AUTH(None)
... defaults.TLS(None)
>>> with defaults.HTTP:
... defaults.ENABLED(False)
... defaults.HOST('')
... defaults.URL('')
... defaults.METHOD('GET')
>>> with defaults.SYSLOG:
... defaults.ENABLED(False)
... defaults.HOST('localhost')
... defaults.PORT(514)
... defaults.FACILITY('LOG_USER')
>>> config = With(defaults, required).freeze()
>>> with config.LOG as LOG:
... LOG.NAME
... 'root'
... LOG.LEVEL
... 30
>>> with config.STREAM as STREAM:
... STREAM.LEVEL
... 30
... STREAM.STDOUT
... True
>>> with config.ROTATE as ROTATE:
... ROTATE.ENABLED
... False
... ROTATE.BACKUPS
... 1
... ROTATE.INTERVAL
... 'h'

Meanwhile, in some other module…

>>> from stage import env
>>> config = env()
>>> with config.LOG as LOG:
... LOG.LEVEL
... 30
... LOG.DATE
... '%a, %d %b %Y %H:%M:%S'
>>> with config.STREAM as STREAM:
... STREAM.ENABLED
... True
... STREAM.LEVEL
... 30
... STREAM.STDOUT
... True
>>> with config.ROTATE as ROTATE:
... ROTATE.ENABLED
... False
... ROTATE.BACKUPS
... 1
... ROTATE.INTERVAL
... 'h'

Spooky.