Fixed #1321 -- Made DJANGO_SETTINGS_MODULE optional. You can now call django.conf.settings.configure() to set settings manually if you don't have a settings module. Thanks, Malcolm Tredinnick, Luke Plant, Fredrik Lundh

git-svn-id: http://code.djangoproject.com/svn/django/trunk@2927 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/conf/__init__.py

@@ -12,10 +12,61 @@ from django.conf import global_settings
 
 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,
+    Django uses the settings module 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):
-
         # update this dict from global settings (but only for ALL_CAPS settings)
         for setting in dir(global_settings):
             if setting == setting.upper():
@@ -27,7 +78,7 @@ class Settings:
         try:
             mod = __import__(self.SETTINGS_MODULE, '', '', [''])
         except ImportError, e:
-            raise EnvironmentError, "Could not import settings '%s' (is it on sys.path?): %s" % (self.SETTINGS_MODULE, e)
+            raise EnvironmentError, "Could not import settings '%s' (Is it on sys.path? Does it have syntax errors?): %s" % (self.SETTINGS_MODULE, e)
 
         # Settings that should be converted into tuples if they're mistakenly entered
         # as strings.
@@ -56,18 +107,32 @@ class Settings:
         # 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/template/defaultfilters.py

@@ -327,14 +327,18 @@ def get_digit(value, arg):
 # 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):
@@ -435,7 +439,7 @@ def pprint(value):
         return pformat(value)
     except Exception, e:
         return "Error in formatting:%s" % e
-    
+
 # Syntax: register.filter(name of filter, callback)
 register.filter(add)
 register.filter(addslashes)

django/utils/translation.py

@@ -117,9 +117,12 @@ def translation(language):
 
     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):
 
@@ -155,7 +158,7 @@ def translation(language):
                 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:

docs/i18n.txt

@@ -540,6 +540,17 @@ you can override base translations in your project path. Or, you can just build
 a big project out of several apps and put all translations into one big project
 message file. The choice is yours.
 
+.. note::
+
+    If you're 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
+    the location of the project directory. (Django normally uses the location
+    of the settings file to determine this, and a settings file doesn't exist
+    if you're manually configuring your settings.)
+
+.. _settings documentation: 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/settings.txt

@@ -724,3 +724,70 @@ Django apps. Just follow these conventions:
     * 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 setting DJANGO_SETTINGS_MODULE
+=====================================================
+
+In some cases, you might want to bypass the ``DJANGO_SETTINGS_MODULE``
+environment variable. For example, if you're using the template system by
+itself, you likely don't want to have to set up an environment variable
+pointing to a settings module.
+
+In these cases, you can configure Django's settings manually. Do this by
+calling ``django.conf.settings.configure()``.
+
+Example::
+
+    from django.conf import settings
+
+    settings.configure(DEBUG=True, TEMPLATE_DEBUG=True,
+        TEMPLATE_DIRS=('/home/web-apps/myapp', '/home/web-apps/base'))
+
+Pass ``configure()`` as many keyword arguments as you'd like, with each keyword
+argument representing a setting and its value. Each argument name should be all
+uppercase, with the same name as the settings described above. If a particular
+setting is not passed to ``configure()`` and is needed at some later point,
+Django will use the default setting value.
+
+Custom default settings
+-----------------------
+
+If you'd 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()``.
+
+In this example, default settings are taken from ``myapp_defaults``, and the
+``DEBUG`` setting is set to ``True``, regardless of its value in
+``myapp_defaults``::
+
+    from django.conf import settings
+    from myapp import myapp_defaults
+
+    settings.configure(default_settings=myapp_defaults, DEBUG=True)
+
+The following example, which uses ``myapp_defaults`` as a positional argument,
+is equivalent::
+
+    settings.configure(myapp_defaults, DEBUG = True)
+
+Either configure() or DJANGO_SETTINGS_MODULE is required
+--------------------------------------------------------
+
+If you're not setting the ``DJANGO_SETTINGS_MODULE`` environment variable, you
+*must* call ``configure()`` at some point before using any code that reads
+settings.
+
+If you don't set ``DJANGO_SETTINGS_MODULE`` and don't call ``configure()``,
+Django will raise an ``EnvironmentError`` exception the first time a setting
+is accessed.
+
+If you set ``DJANGO_SETTINGS_MODULE``, access settings values somehow, *then*
+call ``configure()``, Django will raise an ``EnvironmentError`` saying settings
+have already been configured.
+
+Also, it's an error to call ``configure()`` more than once, or to call
+``configure()`` after any setting has been accessed.
+
+It boils down to this: Use exactly one of either ``configure()`` or
+``DJANGO_SETTINGS_MODULE``. Not both, and not neither.

docs/templates_python.txt

@@ -7,6 +7,10 @@ perspective -- how it works and how to extend it. If you're just looking for
 reference on the language syntax, see
 `The Django template language: For template authors`_.
 
+If you're looking to use the Django template system as part of another
+application -- i.e., without the rest of the framework -- make sure to read
+the `configuration`_ section later in this document.
+
 .. _`The Django template language: For template authors`: http://www.djangoproject.com/documentation/templates/
 
 Basics
@@ -876,3 +880,37 @@ The only new concept here is the ``self.nodelist.render(context)`` in
 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. But if you're using the
+template system independently of the rest of Django, the environment variable
+approach isn't very convenient, because you probably want to configure the
+template system in line with the rest of your application rather than dealing
+with settings files and pointing to them via environment variables.
+
+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 specify. 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``. All available settings are described in the
+`settings documentation`_, and any setting starting with *TEMPLATE_*
+is 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/

tests/othertests/templates.py

@@ -507,4 +507,5 @@ def run_tests(verbosity=0, standalone=False):
         raise Exception, msg
 
 if __name__ == "__main__":
+    settings.configure()
     run_tests(1, True)

tests/runtests.py

@@ -73,6 +73,10 @@ class TestRunner:
     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()]