Fleshed out AppConfig objects.

Marginally improved creation of AppConfig stubs for non-installed apps.

django/apps/base.py

@@ -1,25 +1,46 @@
 from collections import OrderedDict
 
+from django.utils._os import upath
+
 
 class AppConfig(object):
     """
     Class representing a Django application and its configuration.
     """
 
-    def __init__(self, label, models_module=None, installed=True):
+    def __init__(self, name, app_module, models_module):
+        # Full Python path to the application eg. 'django.contrib.admin'.
+        # This is the value that appears in INSTALLED_APPS.
+        self.name = name
+
         # Last component of the Python path to the application eg. 'admin'.
-        self.label = label
+        # This value must be unique across a Django project.
+        self.label = name.rpartition(".")[2]
+
+        # Root module eg. <module 'django.contrib.admin' from
+        # 'django/contrib/admin/__init__.pyc'>.
+        self.app_module = app_module
 
         # Module containing models eg. <module 'django.contrib.admin.models'
         # from 'django/contrib/admin/models.pyc'>.
         self.models_module = models_module
 
         # Mapping of lower case model names to model classes.
+        # Populated by AppCache.register_models().
         self.models = OrderedDict()
 
         # Whether the app is in INSTALLED_APPS or was automatically created
         # when one of its models was imported.
-        self.installed = installed
+        self.installed = app_module is not None
+
+        # Filesystem path to the application directory eg.
+        # u'/usr/lib/python2.7/dist-packages/django/contrib/admin'.
+        # This is a unicode object on Python 2 and a str on Python 3.
+        self.path = upath(app_module.__path__[0]) if app_module is not None else None
+
+    @classmethod
+    def _stub(cls, label):
+        return cls(label, None, None)
 
     def __repr__(self):
         return '<AppConfig: %s>' % self.label

django/apps/cache.py

@@ -133,16 +133,15 @@ class BaseAppCache(object):
                     raise
 
         self.nesting_level -= 1
-        label = self._label_for(models_module)
+
-        try:
+        app_config = AppConfig(
-            app_config = self.app_configs[label]
+            name=app_name, app_module=app_module, models_module=models_module)
-        except KeyError:
+        # If a stub config existed for this app, preserve models registry.
-            self.app_configs[label] = AppConfig(
+        old_app_config = self.app_configs.get(app_config.label)
-                label=label, models_module=models_module)
+        if old_app_config is not None:
-        else:
+            app_config.models = old_app_config.models
-            if not app_config.installed:
+        self.app_configs[app_config.label] = app_config
-                app_config.models_module = models_module
+
-                app_config.installed = True
         return models_module
 
     def app_cache_ready(self):
@@ -318,8 +317,7 @@ class BaseAppCache(object):
             try:
                 app_config = self.app_configs[app_label]
             except KeyError:
-                app_config = AppConfig(
+                app_config = AppConfig._stub(app_label)
-                    label=app_label, installed=False)
                 self.app_configs[app_label] = app_config
         for model in models:
             # Add the model to the app_config's models dictionary.