"Functions that help with dynamically creating decorators for views."

import types

try:

    from functools import wraps

except ImportError:

    from django.utils.functional import wraps  # Python 2.3, 2.4 fallback.

def decorator_from_middleware(middleware_class):

    """

    Given a middleware class (not an instance), returns a view decorator. This

    lets you use middleware functionality on a per-view basis.

    """

    def _decorator_from_middleware(*args, **kwargs):

        # For historical reasons, these "decorators" are also called as

        # dec(func, *args) instead of dec(*args)(func). We handle both forms

        # for backwards compatibility.

        has_func = True

        try:

            view_func = kwargs.pop('view_func')

        except KeyError:

            if len(args):

                view_func, args = args[0], args[1:]

            else:

                has_func = False

        if not (has_func and isinstance(view_func, types.FunctionType)):

            # We are being called as a decorator.

            if has_func:

                args = (view_func,) + args

            middleware = middleware_class(*args, **kwargs)

            def decorator_func(fn):

                return _decorator_from_middleware(fn, *args, **kwargs)

            return decorator_func

        middleware = middleware_class(*args, **kwargs)

        def _wrapped_view(request, *args, **kwargs):

            if hasattr(middleware, 'process_request'):

                result = middleware.process_request(request)

                if result is not None:

                    return result

            if hasattr(middleware, 'process_view'):

                result = middleware.process_view(request, view_func, args, kwargs)

                if result is not None:

                    return result

            try:

                response = view_func(request, *args, **kwargs)

            except Exception, e:

                if hasattr(middleware, 'process_exception'):

                    result = middleware.process_exception(request, e)

                    if result is not None:

                        return result

                raise

            if hasattr(middleware, 'process_response'):

                result = middleware.process_response(request, response)

                if result is not None:

                    return result

            return response

        return wraps(view_func)(_wrapped_view)

    return _decorator_from_middleware