newforms-admin: First-draft implementation of AdminSite

git-svn-id: http://code.djangoproject.com/svn/django/branches/newforms-admin@4581 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/admin/__init__.py

@@ -0,0 +1,2 @@
+from django.contrib.admin.options import ModelAdmin
+from django.contrib.admin.sites import AdminSite, site

django/contrib/admin/sites.py

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+from django.contrib.admin import ModelAdmin
+from django.db.models import Model
+
+class AlreadyRegistered(Exception):
+    pass
+
+class NotRegistered(Exception):
+    pass
+
+class AdminSite(object):
+    def __init__(self):
+        self._registry = {} # model_class -> admin_class
+
+    def register(model_or_iterable, admin_class=None, **options):
+        """
+        Registers the given model(s) with the given admin class.
+
+        If an admin class isn't given, it will use ModelAdmin (the default
+        admin options). If keyword arguments are given -- e.g., list_display --
+        they'll be applied as options to the admin class.
+
+        If a model is already registered, this will raise AlreadyRegistered.
+        """
+        admin_class = admin_class or ModelAdmin
+        # TODO: Handle options
+        if issubclass(model_or_iterable, Model):
+            model_or_iterable = [model_or_iterable]
+        for model in model_or_iterable:
+            if model in self._registry:
+                raise AlreadyRegistered('The model %s is already registered' % model.__class__.__name__)
+            self._registry[model] = admin_class
+
+    def unregister(model_or_iterable):
+        if issubclass(model_or_iterable, Model):
+            model_or_iterable = [model_or_iterable]
+        for model in model_or_iterable:
+            if model not in self._registry:
+                raise NotRegistered('The model %s is not registered' % model.__class__.__name__)
+            del self._registry[model]
+
+# This global object represents the default admin site, for the common case.
+# You can instantiate AdminSite in your own code to create a custom admin site.
+site = AdminSite()