Cleaned up code in django.conf.settings to move DJANGO_SETTINGS_MODULE into a variable, so other scripts can introspect it. Also made it display a better error message if DJANGO_SETTINGS_MODULE is set to the empty string

git-svn-id: http://code.djangoproject.com/svn/django/trunk@239 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/conf/settings.py

@@ -10,6 +10,8 @@ import os
 import sys
 from django.conf import global_settings
 
+ENVIRONMENT_VARIABLE = "DJANGO_SETTINGS_MODULE"
+
 # get a reference to this module (why isn't there a __module__ magic var?)
 me = sys.modules[__name__]
 
@@ -20,14 +22,16 @@ for setting in dir(global_settings):
 
 # try to load DJANGO_SETTINGS_MODULE
 try:
-    me.SETTINGS_MODULE = os.environ["DJANGO_SETTINGS_MODULE"]
+    me.SETTINGS_MODULE = os.environ[ENVIRONMENT_VARIABLE]
+    if not me.SETTINGS_MODULE: # If it's set but is an empty string.
+        raise KeyError
 except KeyError:
-    raise EnvironmentError, "Environment variable DJANGO_SETTINGS_MODULE is undefined."
+    raise EnvironmentError, "Environment variable %s is undefined." % ENVIRONMENT_VARIABLE
 
 try:
     mod = __import__(me.SETTINGS_MODULE, '', '', [''])
 except ImportError, e:
-    raise EnvironmentError, "Could not import DJANGO_SETTINGS_MODULE '%s' (is it on sys.path?): %s" % (me.SETTINGS_MODULE, e)
+    raise EnvironmentError, "Could not import %s '%s' (is it on sys.path?): %s" % (ENVIRONMENT_VARIABLE, me.SETTINGS_MODULE, e)
 
 # Settings that should be converted into tuples if they're mistakenly entered
 # as strings.
@@ -41,7 +45,7 @@ for setting in dir(mod):
         setattr(me, setting, setting_value)
 
 # save DJANGO_SETTINGS_MODULE in case anyone in the future cares
-me.SETTINGS_MODULE = os.environ.get('DJANGO_SETTINGS_MODULE', '')
+me.SETTINGS_MODULE = os.environ.get(ENVIRONMENT_VARIABLE, '')
 
 # move the time zone info into os.environ
 os.environ['TZ'] = me.TIME_ZONE
@@ -51,4 +55,3 @@ for k in dir(me):
     if not k.startswith('_') and k != 'me' and k != k.upper():
         delattr(me, k)
 del me, k
-