make sure original object is not modified, and auto-generate some

required common properties..

ui/cli.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 
+import copy
 import datetime
 import hashlib
 import pasn1
@@ -22,13 +23,22 @@ class MDBase(object):
 	'''This is a simple wrapper that turns a JSON object into a pythonesc
 	object where attribute accesses work.'''
 
-	_common_properties = [ 'uuid', 'type', 'modified', 'created_by_ref' ]
+	_generated_properties = {
+		'uuid': uuid.uuid4,
+		'modified': datetime.datetime.utcnow
+	}
+	_common_properties = [ 'type', 'created_by_ref' ]
 
 	def __init__(self, obj):
+		obj = copy.deepcopy(obj)
 		for x in self._common_properties:
 			if x not in obj:
 				raise ValueError('common property %s not present' % `x`)
 
+		for x, fun in self._generated_properties.iteritems():
+			if x not in obj:
+				obj[x] = fun()
+
 		self._obj = obj
 
 	@classmethod
@@ -230,6 +240,15 @@ class _TestCases(unittest.TestCase):
 		self.assertRaises(ValueError, MDBase.create_obj, { 'type': 'unknosldkfj' })
 		self.assertRaises(ValueError, MDBase.create_obj, { 'type': 'metadata' })
 
+		baseobj = {
+			'type': 'metadata',
+			'created_by_ref': '867c7563-79ae-435c-a265-9d8509cefac5',
+		}
+		origbase = copy.deepcopy(baseobj)
+		md = MDBase.create_obj(baseobj)
+
+		self.assertEqual(baseobj, origbase)
+
 	def test_makehash(self):
 		self.assertRaises(ValueError, ObjectStore.makehash, 'slkj')
 		self.assertRaises(ValueError, ObjectStore.makehash, 'sha256:91751cee0a1ab8414400238a761411daa29643ab4b8243e9a91649e25be53ADA')