Python style: lowercase class names for "namespaces"?

Question

I know the PEP-8 convention for class names is ClassName. But we often use small classes as pseudo-namespaces, enums etc. In other words, not a real class that you're going to instantiate. We've opted for a lowercase naming convention for such "classes", because they're really a namespace/enum name.

Does anyone else have in-house styles for this, or other ways of achieving the same thing?

An example:

import urllib2

class config:  # pseudo-namespace for module-level config variables
    api_url = 'http://example.com/api'
    timeout = 1.5
    debug = True

class countries:  # pseudo-enum
    new_zealand = 1
    united_states = 2

def func():
    if config.debug:
        print 'Calling func()'
    return urllib2.urlopen(config.api_url)

Answer 1

For all enums and constants, I prefer to use capitalized versions.

class COUNTRIES:  # pseudo-enum
    NEW_ZEALAND = 1
    UNITED_STATES = 2

It is still ok with me, if the class name is not all capitalized. Since, any way it is tied up with the enum values. I am always going to use it like Countries.NEW_ZEALAND, which tells me that it is an enum.

class Countries:  # pseudo-enum
    NEW_ZEALAND = 1
    UNITED_STATES = 2

Answer 2

You can also create a module named config with the following content:

api_url = 'http://example.com/api'
timeout = 1.5
debug = True

Answer 3

Why not

class PseudoNamespace: pass

config = PseudoNamespace()
config.api_url = 'http://example.com/api'
config.timeout = 1.5
config.debug = True

countries = PseudoNamespace()
config.new_zealand = 1
config.united_states = 2

if you really care about the PEP?

Answer 4

I use dictionaries instead:

config = dict(
    api_url = 'http://example.com/api',
    timeout = 1.5,
    debug = True)

countries = dict(
    new_zealand = 1,
    united_states = 2)

If you find attribute access cumbersome in a Python dict, try an attrdict:

class attrdict(dict):
    def __init__(self, *args, **kwargs):
        dict.__init__(self, *args, **kwargs)
        self.__dict__ = self

It allows to access dictionary entries with keys that are valid identifiers as attributes, e.g. config.api_url instead of config["api_url"].

Of course I use lower-case names for these.