Source code for tic.conf

"""
This is ported from django.conf
Settings and configuration for Tic.

Values will be read from the module specified by the TIC_SETTINGS_MODULE environment
variable, and then from tic.conf.global_settings; see the global settings file for
a list of all possible variables.
"""

import os
import re

from tic.conf import global_settings
from tic.utils.functional import LazyObject
from tic.utils import importlib

ENVIRONMENT_VARIABLE = "TIC_SETTINGS_MODULE"

class LazySettings(LazyObject):
    """
    A lazy proxy for either global Django settings or a custom settings object.
    The user can manually configure settings prior to using them. Otherwise,
    Django uses the settings module pointed to by DJANGO_SETTINGS_MODULE.
    """
    def _setup(self):
        """
        Load the settings module pointed to by the environment variable. This
        is used the first time we need any settings at all, if the user has not
        previously configured the settings manually.
        """
        try:
            settings_module = os.environ[ENVIRONMENT_VARIABLE]
            if not settings_module: # If it's set but is an empty string.
                raise KeyError
        except KeyError:
            # NOTE: This is arguably an EnvironmentError, but that causes
            # problems with Python's interactive help.
            raise ImportError("Settings cannot be imported, because environment variable %s is undefined." % ENVIRONMENT_VARIABLE)

        self._wrapped = Settings(settings_module)

    def configure(self, default_settings=global_settings, **options):
        """
        Called to manually configure the settings. The 'default_settings'
        parameter sets where to retrieve any unspecified values from (its
        argument must support attribute access (__getattr__)).
        """
        if self._wrapped != None:
            raise RuntimeError('Settings already configured.')
        holder = UserSettingsHolder(default_settings)
        for name, value in options.items():
            setattr(holder, name, value)
        self._wrapped = holder

    def configured(self):
        """
        Returns True if the settings have already been configured.
        """
        return bool(self._wrapped)
    configured = property(configured)

class Settings(object):
    def __init__(self, settings_module):
        # update this dict from global settings (but only for ALL_CAPS settings)
        for setting in dir(global_settings):
            if setting == setting.upper():
                setattr(self, setting, getattr(global_settings, setting))

        # store the settings module in case someone later cares
        self.SETTINGS_MODULE = settings_module

        try:
            mod = importlib.import_module(self.SETTINGS_MODULE)
        except ImportError, e:
            return # since privding a settings file is optional

        for setting in dir(mod):
            if setting == setting.upper():
                setting_value = getattr(mod, setting)
                setattr(self, setting, setting_value)
            

        
class UserSettingsHolder(object):
    """
    Holder for user configured settings.
    """
    # SETTINGS_MODULE doesn't make much sense in the manually configured
    # (standalone) case.
    SETTINGS_MODULE = None

    def __init__(self, default_settings):
        """
        Requests for configuration variables not in this class are satisfied
        from the module specified in default_settings (if possible).
        """
        self.default_settings = default_settings

    def __getattr__(self, name):
        return getattr(self.default_settings, name)

    def __dir__(self):
        return self.__dict__.keys() + dir(self.default_settings)

    # For Python < 2.6:
    __members__ = property(lambda self: self.__dir__())

settings = LazySettings()