Make @handle_errors support any kind of function

This hack lets the @handle_errors decorator be used on
functions, methods, static methods and class methods,
without having to worry about how many parameters the
function takes, and whether there is "self" or not.

Change-Id: Ie34d200939dbadae0771da893e563995cd3ecf45

1 files changed, 21 insertions, 6 deletions

diff --git a/tuskar_ui/handle_errors.py b/tuskar_ui/handle_errors.py
index b1f14a3b..a505f4eb 100644
--- a/tuskar_ui/handle_errors.py
+++ b/tuskar_ui/handle_errors.py
@@ -13,18 +13,20 @@
 #    under the License.
 
 import functools
+import inspect
 
 import horizon.exceptions
 
 
-def handle_errors(error_message, error_default=None):
+def handle_errors(error_message, error_default=None, request_arg=None):
     """A decorator for adding default error handling to API calls.
 
     It wraps the original method in a try-except block, with horizon's
     error handling added.
 
-    Note: it should only be used on methods that take request as the first
-    (second after self or cls) argument.
+    Note: it should only be used on functions or methods that take request as
+    their argument (it has to be named "request", or ``request_arg`` has to be
+    provided, indicating which argument is the request).
 
     The decorated method accepts a number of additional parameters:
 
@@ -35,18 +37,31 @@ def handle_errors(error_message, error_default=None):
         :param _error_ignore: ignore known errors
     """
     def decorator(func):
+        # XXX This is an ugly hack for finding the 'request' argument.
+        if request_arg is None:
+            for _request_arg, name in enumerate(inspect.getargspec(func).args):
+                if name == 'request':
+                    break
+            else:
+                raise RuntimeError(
+                    "The handle_errors decorator requires 'request' as "
+                    "an argument of the function or method being decorated")
+        else:
+            _request_arg = request_arg
+
         @functools.wraps(func)
-        def wrapper(self, request, *args, **kwargs):
+        def wrapper(*args, **kwargs):
             _error_handle = kwargs.pop('_error_handle', True)
             _error_message = kwargs.pop('_error_message', error_message)
             _error_default = kwargs.pop('_error_default', error_default)
             _error_redirect = kwargs.pop('_error_redirect', None)
             _error_ignore = kwargs.pop('_error_ignore', False)
             if not _error_handle:
-                return func(self, request, *args, **kwargs)
+                return func(*args, **kwargs)
             try:
-                return func(self, request, *args, **kwargs)
+                return func(*args, **kwargs)
             except Exception:
+                request = args[_request_arg]
                 horizon.exceptions.handle(request, _error_message,
                                           ignore=_error_ignore,
                                           redirect=_error_redirect)