Added pristine decorator to handle callable settings. Fixes #28.

CHANGES.rst

@@ -3,6 +3,11 @@
 Changelog
 ---------
 
+v0.3 (unreleased)
+^^^^^^^^^^^^^^^^^
+
+- Added ``pristine`` decorator to be able to have callables as settings.
+
 v0.2.1 (2013-04-11)
 ^^^^^^^^^^^^^^^^^^^
 

configurations/__init__.py

@@ -1,5 +1,6 @@
 # flake8: noqa
 from .base import Settings
+from .decorators import pristine
 
 __version__ = '0.2.1'
-__all__ = ['Settings']
+__all__ = ['Settings', 'pristine']

configurations/decorators.py

@@ -0,0 +1,19 @@
+def pristine(func):
+    """
+    A decorator for handling pristine settings like callables.
+
+    Use it like this::
+
+        from configurations import pristine
+
+        class Develop(Settings):
+
+            @pristine
+            USER_CHECK(user):
+                return user.check_perms()
+
+            GROUP_CHECK = pristine(lambda user: user.has_group_access())
+
+    """
+    func.pristine = True
+    return staticmethod(func)

configurations/importer.py

@@ -161,12 +161,12 @@ class SettingsLoader(object):
                                        "'%s.%s': %s" %
                                        (mod.__name__, self.name, err))
         for name, value in attributes:
-            if callable(value):
+            if callable(value) and not getattr(value, 'pristine', False):
                 try:
                     value = value()
                 except Exception as err:
                     raise ImproperlyConfigured(
-                        "Couldn't execute callable '%s' in '%s.%s': %s" %
+                        "Couldn't call '%s' in '%s.%s': %s" %
                         (value, mod.__name__, self.name, err))
             setattr(mod, name, value)
         setattr(mod, 'CONFIGURATION', '%s.%s' % (fullname, self.name))

configurations/tests/settings/main.py

@@ -1,6 +1,6 @@
 import os
 import uuid
-from configurations import Settings
+from configurations import Settings, pristine
 
 
 class Test(Settings):
@@ -43,6 +43,12 @@ class Test(Settings):
 
     LAMBDA_SETTING = lambda self: 3
 
+    PRISTINE_LAMBDA_SETTING = pristine(lambda: 4)
+
+    @pristine
+    def PRISTINE_FUNCTION_SETTING():
+        return 5
+
     def TEMPLATE_CONTEXT_PROCESSORS(self):
         return Settings.TEMPLATE_CONTEXT_PROCESSORS + (
             'configurations.tests.settings.base.test_callback',)

configurations/tests/test_main.py

@@ -17,6 +17,10 @@ class MainTests(TestCase):
         self.assertEqual(main.PROPERTY_SETTING, 1)
         self.assertEqual(main.METHOD_SETTING, 2)
         self.assertEqual(main.LAMBDA_SETTING, 3)
+        self.assertNotEqual(main.PRISTINE_LAMBDA_SETTING, 4)
+        self.assertTrue(lambda: callable(main.PRISTINE_LAMBDA_SETTING))
+        self.assertNotEqual(main.PRISTINE_FUNCTION_SETTING, 5)
+        self.assertTrue(lambda: callable(main.PRISTINE_FUNCTION_SETTING))
         self.assertEqual(main.TEMPLATE_CONTEXT_PROCESSORS,
                          global_settings.TEMPLATE_CONTEXT_PROCESSORS + (
                              'configurations.tests.settings.base.test_callback',
@@ -26,6 +30,10 @@ class MainTests(TestCase):
         from django.conf import settings
         self.assertEqual(settings.PROPERTY_SETTING, 1)
         self.assertRaises(AttributeError, lambda: settings._PRIVATE_SETTING)
+        self.assertNotEqual(settings.PRISTINE_LAMBDA_SETTING, 4)
+        self.assertTrue(lambda: callable(settings.PRISTINE_LAMBDA_SETTING))
+        self.assertNotEqual(settings.PRISTINE_FUNCTION_SETTING, 5)
+        self.assertTrue(lambda: callable(settings.PRISTINE_FUNCTION_SETTING))
 
     @patch.dict(os.environ, clear=True, DJANGO_CONFIGURATION='Test')
     def test_empty_module_var(self):

docs/index.rst

@@ -131,6 +131,31 @@ a Settings class::
         DEBUG = False
         # ...
 
+Pristines
+^^^^^^^^^
+
+.. versionadded:: 0.3
+
+In case one of your settings itself need to be a callable, you need to
+tell that django-configurations by using the ``pristine`` decorator,
+e.g.::
+
+    from configurations import Settings, pristine
+
+    class Prod(Settings):
+
+        @pristine
+        def ACCESS_FUNCTION(user):
+            return user.is_staff
+
+Lambdas work, too::
+
+    from configurations import Settings, pristine
+
+    class Prod(Settings):
+        ACCESS_FUNCTION = pristine(lamda user: user.is_staff)
+
+
 Alternatives
 ------------