Add safe_utils to the source base

safe_utils.py is a dependency for exception.py as is copied from solum.

Change-Id: I32002b19f9a76d6fea675efe3ebfa886dc20a58e

magnum/common/safe_utils.py

@@ -0,0 +1,55 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# Copyright 2011 Justin Santa Barbara
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""Utilities and helper functions that won't produce circular imports."""
+
+import inspect
+
+
+def getcallargs(function, *args, **kwargs):
+    """This is a simplified inspect.getcallargs (2.7+).
+
+    It should be replaced when python >= 2.7 is standard.
+    """
+    keyed_args = {}
+    argnames, varargs, keywords, defaults = inspect.getargspec(function)
+
+    keyed_args.update(kwargs)
+
+    # NOTE(alaski) the implicit 'self' or 'cls' argument shows up in
+    # argnames but not in args or kwargs.  Uses 'in' rather than '==' because
+    # some tests use 'self2'.
+    if 'self' in argnames[0] or 'cls' == argnames[0]:
+        # The function may not actually be a method or have im_self.
+        # Typically seen when it's stubbed with mox.
+        if inspect.ismethod(function) and hasattr(function, 'im_self'):
+            keyed_args[argnames[0]] = function.im_self
+        else:
+            keyed_args[argnames[0]] = None
+
+    remaining_argnames = filter(lambda x: x not in keyed_args, argnames)
+    keyed_args.update(dict(zip(remaining_argnames, args)))
+
+    if defaults:
+        num_defaults = len(defaults)
+        for argname, value in zip(argnames[-num_defaults:], defaults):
+            if argname not in keyed_args:
+                keyed_args[argname] = value
+
+    return keyed_args