Merge "vFW and vDNS support added to azure-plugin"

[multicloud/azure.git] / azure / aria / aria-extension-cloudify / src / aria / aria / utils / imports.py

diff --git a/azure/aria/aria-extension-cloudify/src/aria/aria/utils/imports.py b/azure/aria/aria-extension-cloudify/src/aria/aria/utils/imports.py
new file mode 100644 (file)
index 0000000..14ad09e
--- /dev/null
+++ b/azure/aria/aria-extension-cloudify/src/aria/aria/utils/imports.py
@@ -0,0 +1,96 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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 for dynamically loading Python code.
+"""
+
+import pkgutil
+import importlib
+
+
+def import_fullname(name, paths=None):
+    """
+    Imports a variable or class based on a full name, optionally searching for it in the paths.
+    """
+    paths = paths or []
+    if name is None:
+        return None
+
+    def do_import(name):
+        if name and ('.' in name):
+            module_name, name = name.rsplit('.', 1)
+            return getattr(__import__(module_name, fromlist=[name], level=0), name)
+        else:
+            raise ImportError('import not found: %s' % name)
+
+    try:
+        return do_import(name)
+    except ImportError:
+        for path in paths:
+            try:
+                return do_import('%s.%s' % (path, name))
+            except Exception as e:
+                raise ImportError('cannot import %s, because %s' % (name, e))
+
+    raise ImportError('import not found: %s' % name)
+
+
+def import_modules(name):
+    """
+    Imports a module and all its sub-modules, recursively. Relies on modules defining a ``MODULES``
+    attribute listing their sub-module names.
+    """
+
+    module = __import__(name, fromlist=['MODULES'], level=0)
+    if hasattr(module, 'MODULES'):
+        for module_ in module.MODULES:
+            import_modules('%s.%s' % (name, module_))
+
+
+# TODO merge with import_fullname
+def load_attribute(attribute_path):
+    """
+    Dynamically load an attribute based on the path to it. E.g.
+    ``some_package.some_module.some_attribute``, will load ``some_attribute`` from the
+    ``some_package.some_module`` module.
+    """
+    module_name, attribute_name = attribute_path.rsplit('.', 1)
+    try:
+        module = importlib.import_module(module_name)
+        return getattr(module, attribute_name)
+    except ImportError:
+        # TODO: handle
+        raise
+    except AttributeError:
+        # TODO: handle
+        raise
+
+
+def iter_modules():
+    # apparently pkgutil had some issues in python 2.6. Accessing any root level directories
+    # failed. and it got the entire process of importing fail. Since we only need any
+    # aria_extension related loading, in the meantime we could try to import only those
+    # (and assume they are not located at the root level.
+    # [In python 2.7 it does actually ignore any OSError].
+    yielded = {}
+    for importer in pkgutil.iter_importers():
+        try:
+            for module_name, ispkg in pkgutil.iter_importer_modules(importer):
+                if module_name not in yielded:
+                    yielded[module_name] = True
+                    yield importer, module_name, ispkg
+        except OSError:
+            pass