Ticket #1321: standalone-django.diff

django/conf/__init__.py

@@ -12 +12 @@
 
 ENVIRONMENT_VARIABLE = "DJANGO_SETTINGS_MODULE"
 
+class LazySettings:
+    """
+    A lazy proxy for either global django settings or a custom settings object.
+    The user can manually configure settings prior to using them, otherwise the
+    standard settings, pointed to by DJANGO_SETTINGS_MODULE.
+    """
+    def __init__(self):
+        # _target must be either None or something that supports attribute
+        # access (getattr, hasattr, etc).
+        self._target = None
+
+    def __getattr__(self, name):
+        if self._target is None:
+            self._import_settings()
+        if name == '__members__':
+            # Used to implement dir(obj), for example.
+            return self._target.get_all_members()
+        return getattr(self._target, name)
+
+    def __setattr__(self, name, value):
+        if name == '_target':
+            self.__dict__['_target'] = value
+        else:
+            setattr(self._target, name, value)
+
+    def _import_settings(self):
+        """
+        Load the settings module pointed to by the environment variable. This
+        is used the first time we need any settings at all, if the user has not
+        previously configured the settings manually.
+        """
+        try:
+            settings_module = os.environ[ENVIRONMENT_VARIABLE]
+            if not settings_module: # If it's set but is an empty string.
+                raise KeyError
+        except KeyError:
+            raise EnvironmentError, "Environment variable %s is undefined." % ENVIRONMENT_VARIABLE
+
+        self._target = Settings(settings_module)
+
+    def configure(self, default_settings = global_settings, **options):
+        """
+        Called to manually configure the settings. The 'default_settings'
+        parameter sets where to retrieve any unspecified values from (its
+        argument must support attribute access (__getattr__).
+        """
+        if self._target != None:
+            raise EnvironmentError('Settings already configured.')
+        holder = UserSettingsHolder(default_settings)
+        for name, value in options.items():
+            setattr(holder, name, value)
+        self._target = holder
+
+
 class Settings:
 
     def __init__(self, settings_module):
@@ -56 +110 @@
         # move the time zone info into os.environ
         os.environ['TZ'] = self.TIME_ZONE
 
-# try to load DJANGO_SETTINGS_MODULE
-try:
-    settings_module = os.environ[ENVIRONMENT_VARIABLE]
-    if not settings_module: # If it's set but is an empty string.
-        raise KeyError
-except KeyError:
-    raise EnvironmentError, "Environment variable %s is undefined." % ENVIRONMENT_VARIABLE
+    def get_all_members(self):
+        return dir(self)
 
-# instantiate the configuration object
-settings = Settings(settings_module)
+class UserSettingsHolder:
+    """
+    Holder for user configured settings.
+    """
+    # SETTINGS_MODULE does not really make sense in the manually configured
+    # (standalone) case.
+    SETTINGS_MODULE = None
 
+    def __init__(self, default_settings):
+        """
+        Requests for configuration variables not in this class are satisfied
+        from the module specified in default_settings (if possible).
+        """
+        self.default_settings = default_settings
+
+    def __getattr__(self, name):
+        return getattr(self.default_settings, name)
+
+    def get_all_members(self):
+        return dir(self) + dir(self.default_settings)
+
+settings = LazySettings()
+
 # install the translation machinery so that it is available
 from django.utils import translation
 translation.install()

django/utils/translation.py

@@ -117 +117 @@
 
     globalpath = os.path.join(os.path.dirname(sys.modules[settings.__module__].__file__), 'locale')
 
-    parts = settings.SETTINGS_MODULE.split('.')
-    project = __import__(parts[0], {}, {}, [])
-    projectpath = os.path.join(os.path.dirname(project.__file__), 'locale')
+    if settings.SETTINGS_MODULE is not None:
+        parts = settings.SETTINGS_MODULE.split('.')
+        project = __import__(parts[0], {}, {}, [])
+        projectpath = os.path.join(os.path.dirname(project.__file__), 'locale')
+    else:
+        projectpath = None
 
     def _fetch(lang, fallback=None):
 
@@ -155 +158 @@
                 if os.path.isdir(localepath):
                     res = _merge(localepath)
 
-        if os.path.isdir(projectpath):
+        if projectpath and os.path.isdir(projectpath):
             res = _merge(projectpath)
 
         for appname in settings.INSTALLED_APPS:

django/template/defaultfilters.py

@@ -327 +327 @@
 # DATES           #
 ###################
 
-def date(value, arg=settings.DATE_FORMAT):
+def date(value, arg = None):
     "Formats a date according to the given format"
     from django.utils.dateformat import format
+    if arg is None:
+        arg = settings.DATE_FORMAT
     return format(value, arg)
 
-def time(value, arg=settings.TIME_FORMAT):
+def time(value, arg = None):
     "Formats a time according to the given format"
     from django.utils.dateformat import time_format
+    if arg is None:
+            arg = settings.TIME_FORMAT
     return time_format(value, arg)
 
 def timesince(value):

tests/othertests/templates.py

@@ -507 +507 @@
         raise Exception, msg
 
 if __name__ == "__main__":
+    settings.configure()
     run_tests(1, True)

tests/runtests.py

@@ -73 +73 @@
     def run_tests(self):
         from django.conf import settings
 
+        # An empty access of the settings to force the default options to be
+        # installed prior to assigning to them.
+        settings.INSTALLED_APPS
+
         # Manually set INSTALLED_APPS to point to the test models.
         settings.INSTALLED_APPS = [MODEL_TESTS_DIR_NAME + '.' + a for a in get_test_models()]
 

docs/settings.txt

@@ -724 +724 @@
     * For settings that are sequences, use tuples instead of lists. This is
       purely for performance.
     * Don't reinvent an already-existing setting.
+
+Using settings without the DJANGO_SETTINGS_MODULE environment variable
+=======================================================================
+
+In some very special circumstances, it is not appropriate to read the
+configuration module's name from an environment variable. For example, if you
+are using the templating or view system as part of another system, without
+running a full Django setup, you will want to be able to import the
+appropriate subsystem and configure it just before you use it.
+
+In these cases, you can configure Django's settings manually (and, indeed, you
+*must* do so if you are not setting the DJANGO_SETTINGS_MODULE environment
+variable). The ``configure()`` method in ``django.conf.settings`` is the way
+to do this.
+
+.. note::
+
+    You must call ``configure()`` prior to running any method that uses the
+    settings or reading any attributes from ``django.conf.settings`` yourself.
+    As soon as anything accesses ``django.conf.settings``, the module
+    specified in ``DJANGO_SETTINGS_MODULE`` is loaded, unless you have
+    previously called ``configure()`` and an error results if the environment
+    variable is not set correctly.
+
+    It is an error to call ``configure()`` more than once or to call
+    ``configure()`` after any setting has been accessed. This is in line with
+    the admonishment earlier in this document about not writing to
+    ``settings`` at all. Configure your settings early and then leave them
+    fixed.
+
+The call to ``configure()`` takes any number of keyword arguments specifying
+settings and their values. These keywords are all uppercase values with the
+same names as the settings described above. If a particular setting is not
+passed to ``configure()`` and is needed at some later point, the default value
+from ``django.conf.global_settings`` is used.
+
+Example::
+
+    from django.conf import settings
+
+    settings.configure(DEBUG = True, TEMPLATE_DEBUG = True, 
+            TEMPLATE_DIRS = ('/home/web-apps/myapp/',))
+
+Following this setup call, if some subsequent calls need, for example, to use
+the value of ``setings.TEMPLATE_LOADERS``, the default value will be used.
+
+If, for some reason, you would like default values to come from somewhere
+other than ``django.conf.global_settings``, you can pass in a module or class
+that provides the default settings as the ``default_settings`` argument (or as
+the first positional argument) in the call to ``configure()``. For example::
+
+    from django.conf import settings
+    from myapp import myapp_defaults
+
+    settings.configure(default_settings = myapp_defaults, DEBUG = True)
+
+    # Now all defaults will be taken from myapp_defaults and DEBUG will be
+    # set as requested.
+    #
+    # settings.configure(myapp_defaults, DEBUG = True) would also have worked.
+

docs/i18n.txt

@@ -540 +540 @@
 a big project out of several apps and put all translations into one big project
 message file. The choice is yours.
 
+.. note::
+
+    If you are using manually configured settings as described in the
+    `settings`_ documentation, the ``locale`` directory in the project directory
+    will not be examined, since Django loses the ability to work out where the
+    project directory is (it normally uses the location of the settings file
+    to determine this and this file does not exist in the manually configured
+    case).
+
+.. _settings: http://www.djangoproject.com/documentation/settings/#using-settings-without-the-django-settings-module-environment-variable
+
 All message file repositories are structured the same way. They are:
 
     * ``$APPPATH/locale/<language>/LC_MESSAGES/django.(po|mo)``

docs/templates_python.txt

@@ -7 +7 @@
 reference on the language syntax, see
 `The Django template language: For template authors`_.
 
+If you are looking to use the Django template system as part of another
+application, make sure to read the `configuration`_ section later in this
+document for how to configure the template system after importing the right
+pieces.
+
 .. _`The Django template language: For template authors`: http://www.djangoproject.com/documentation/templates/
 
 Basics
@@ -876 +881 @@
 For more examples of complex rendering, see the source code for ``{% if %}``,
 ``{% for %}``, ``{% ifequal %}`` and ``{% ifchanged %}``. They live in
 ``django/template/defaulttags.py``.
+
+.. _configuration:
+
+Configuring the template system in standalone mode
+===================================================
+
+.. note::
+
+    This section is only of interest to people trying to use the template
+    system as an output component in another application. If you are using the
+    template system as part of a Django application, nothing here applies to
+    you.
+
+Normally, Django will load all the configuration information it needs from its
+own default configuration file, combined with the settings in the module given
+in the ``DJANGO_SETTINGS_MODULE`` environment variable. When using the
+template system independently of the rest of Django, the environment variable
+approach is not very convenient because you probably want to configure the
+template system in line with the rest of your application.
+
+To solve this problem, you need to use the manual configuration option
+described in the `settings file`_ documentation. Simply import the appropriate
+pieces of the templating system and then, *before* you call any of the
+templating functions, call ``django.conf.settings.configure()`` with any
+settings you wish to make. You might want to consider setting at least
+``TEMPLATE_DIRS`` (if you are going to use template loaders),
+``DEFAULT_CHARSET`` (although the default of ``utf-8`` is probably fine) and
+``TEMPLATE_DEBUG``. The full set of available settings are described in the
+`settings documentation`_ and any settings starting with the word *TEMPLATE_*
+are of obvious interest.
+
+.. _settings file: http://www.djangoproject.com/documentation/settings/#using-settings-without-the-django-settings-module-environment-variable
+.. _settings documentation: http://www.djangoproject.com/documentation/settings/
+