Removed some import-time dependencies on Django's settings.

Now you can import the file storage stuff and still call settings.configure()
afterwards. There is still one import-time usage of settings in
django.contrib.comments, but that's unavoidable.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9946 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/files/storage.py

@@ -4,11 +4,12 @@ import urlparse
 
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured, SuspiciousOperation
-from django.utils.encoding import force_unicode
-from django.utils.text import get_valid_filename
-from django.utils._os import safe_join
 from django.core.files import locks, File
 from django.core.files.move import file_move_safe
+from django.utils.encoding import force_unicode
+from django.utils.functional import LazyObject
+from django.utils.text import get_valid_filename
+from django.utils._os import safe_join
 
 __all__ = ('Storage', 'FileSystemStorage', 'DefaultStorage', 'default_storage')
 
@@ -116,12 +117,20 @@ class Storage(object):
         """
         raise NotImplementedError()
 
+    # Needed by django.utils.functional.LazyObject (via DefaultStorage).
+    def get_all_members(self):
+        return self.__members__
+
 class FileSystemStorage(Storage):
     """
     Standard filesystem storage
     """
 
-    def __init__(self, location=settings.MEDIA_ROOT, base_url=settings.MEDIA_URL):
+    def __init__(self, location=None, base_url=None):
+        if location is None:
+            location = settings.MEDIA_ROOT
+        if base_url is None:
+            base_url = settings.MEDIA_URL
         self.location = os.path.abspath(location)
         self.base_url = base_url
 
@@ -212,7 +221,9 @@ class FileSystemStorage(Storage):
             raise ValueError("This file is not accessible via a URL.")
         return urlparse.urljoin(self.base_url, name).replace('\\', '/')
 
-def get_storage_class(import_path):
+def get_storage_class(import_path=None):
+    if import_path is None:
+        import_path = settings.DEFAULT_FILE_STORAGE
     try:
         dot = import_path.rindex('.')
     except ValueError:
@@ -227,5 +238,8 @@ def get_storage_class(import_path):
     except AttributeError:
         raise ImproperlyConfigured('Storage module "%s" does not define a "%s" class.' % (module, classname))
 
-DefaultStorage = get_storage_class(settings.DEFAULT_FILE_STORAGE)
+class DefaultStorage(LazyObject):
+    def _setup(self):
+        self._wrapped = get_storage_class()()
+
 default_storage = DefaultStorage()