i18n - Make string translatable

Since internationalization should be enabled in Watcher, this
patchset refactors the Watcher codebase to wrap previously
untranslatable strings with i18n translation functions so we can
import them for translation into the .pot template file.

Partially Implements: blueprint support-translation
Change-Id: I425967a60b5a7957f753894e5d2ba0d2c5009d1d

watcher/decision_engine/model/model_root.py

@@ -15,12 +15,11 @@
 # limitations under the License.
 from oslo_log import log
 
-from watcher.common.exception import HypervisorNotFound
-from watcher.common.exception import IllegalArgumentException
-from watcher.common.exception import VMNotFound
-from watcher.decision_engine.model.hypervisor import Hypervisor
-from watcher.decision_engine.model.mapping import Mapping
-from watcher.decision_engine.model.vm import VM
+from watcher._i18n import _
+from watcher.common import exception
+from watcher.decision_engine.model import hypervisor
+from watcher.decision_engine.model import mapping
+from watcher.decision_engine.model import vm
 
 LOG = log.getLogger(__name__)
 
@@ -29,18 +28,18 @@ class ModelRoot(object):
     def __init__(self):
         self._hypervisors = {}
         self._vms = {}
-        self.mapping = Mapping(self)
+        self.mapping = mapping.Mapping(self)
         self.resource = {}
 
-    def assert_hypervisor(self, hypervisor):
-        if not isinstance(hypervisor, Hypervisor):
-            raise IllegalArgumentException(
-                "Hypervisor must be an instance of hypervisor")
+    def assert_hypervisor(self, obj):
+        if not isinstance(obj, hypervisor.Hypervisor):
+            raise exception.IllegalArgumentException(
+                _("'obj' argument type is not valid"))
 
-    def assert_vm(self, vm):
-        if not isinstance(vm, VM):
-            raise IllegalArgumentException(
-                "VM must be an instance of VM")
+    def assert_vm(self, obj):
+        if not isinstance(obj, vm.VM):
+            raise exception.IllegalArgumentException(
+                _("'obj' argument type is not valid"))
 
     def add_hypervisor(self, hypervisor):
         self.assert_hypervisor(hypervisor)
@@ -49,7 +48,7 @@ class ModelRoot(object):
     def remove_hypervisor(self, hypervisor):
         self.assert_hypervisor(hypervisor)
         if str(hypervisor.uuid) not in self._hypervisors.keys():
-            raise HypervisorNotFound(hypervisor.uuid)
+            raise exception.HypervisorNotFound(hypervisor.uuid)
         else:
             del self._hypervisors[hypervisor.uuid]
 
@@ -62,12 +61,12 @@ class ModelRoot(object):
 
     def get_hypervisor_from_id(self, hypervisor_uuid):
         if str(hypervisor_uuid) not in self._hypervisors.keys():
-            raise HypervisorNotFound(hypervisor_uuid)
+            raise exception.HypervisorNotFound(hypervisor_uuid)
         return self._hypervisors[str(hypervisor_uuid)]
 
     def get_vm_from_id(self, uuid):
         if str(uuid) not in self._vms.keys():
-            raise VMNotFound(uuid)
+            raise exception.VMNotFound(uuid)
         return self._vms[str(uuid)]
 
     def get_all_vms(self):