How to load (optional) Django apps only if they're present (from http://blog.jupo.org/post/586256417/optional-django-apps)

load_optional_django_apps.py

LOAD_OPTIONAL_APPS = True

if LOAD_OPTIONAL_APPS:
    # <copypaste from="http://blog.jupo.org/post/586256417/optional-django-apps">
    # Define any settings specific to each of the optional apps.
    #
    import sys
    USE_SOUTH = not (len(sys.argv) > 1 and sys.argv[1] == "test")
    DEBUG_TOOLBAR_CONFIG = {"INTERCEPT_REDIRECTS": True}

    # Sequence for each optional app as a dict containing info about the app.
    OPTIONAL_APPS = (
        {"import": "django_extensions", "apps": ("django_extensions",)},
        {"import": "debug_toolbar", "apps": ("debug_toolbar",),
            "middleware": ("debug_toolbar.middleware.DebugToolbarMiddleware",)},
        {"import": "south", "apps": ("south",), "condition": USE_SOUTH},
    )

    # Set up each optional app if available.
    for app in OPTIONAL_APPS:
        if app.get("condition", True):
            try:
                __import__(app["import"])
            except ImportError:
                pass
            else:
                INSTALLED_APPS += app.get("apps", ())
                MIDDLEWARE_CLASSES += app.get("middleware", ())
                TEMPLATE_CONTEXT_PROCESSORS += app.get("context_processors", ())
    #
    # </copypaste>