Fix typos, add to Property class documentation, small performance

boosts, and let strings and booleans in a ListProperty be handled by
__call__().

stix2/__init__.py

@@ -13,12 +13,7 @@ from .utils import get_dict
 from . import exceptions
 
 
-def parse(data):
-    """Deserialize a string or file-like object into a STIX object"""
-
-    obj = get_dict(data)
-
-    obj_map = {
+OBJ_MAP = {
     'attack-pattern': AttackPattern,
     'campaign': Campaign,
     'course-of-action': CourseOfAction,
@@ -34,14 +29,20 @@ def parse(data):
     'tool': Tool,
     'sighting': Sighting,
     'vulnerability': Vulnerability,
-    }
+}
+
+
+def parse(data):
+    """Deserialize a string or file-like object into a STIX object"""
+
+    obj = get_dict(data)
 
     if 'type' not in obj:
         # TODO parse external references, kill chain phases, and granular markings
         pass
     else:
         try:
-            obj_class = obj_map[obj['type']]
+            obj_class = OBJ_MAP[obj['type']]
             return obj_class(**obj)
         except KeyError:
             # TODO handle custom objects

stix2/other.py

@@ -39,7 +39,7 @@ class TLPMarking(_STIXBase):
 
 class StatementMarking(_STIXBase):
     _properties = {
-        'statement': Property(required=True)
+        'statement': StringProperty(required=True)
     }
 
     def __init__(self, statement=None, **kwargs):

stix2/properties.py

@@ -42,9 +42,15 @@ class Property(object):
             to use the same default value, so calling now() for each field--
             likely several microseconds apart-- does not work.
 
-    Subclasses can instead provide a lambda function for `default as a keyword
+    Subclasses can instead provide a lambda function for `default` as a keyword
     argument. `clean` should not be provided as a lambda since lambdas cannot
     raise their own exceptions.
+
+    When instantiating Properties, `required` and `default` should not be used
+    together. `default` implies that the field is required in the specification
+    so this function will be used to supply a value if none is provided.
+    `required` means that the user must provide this; it is required in the
+    specification and we can't or don't want to create a default value.
     """
 
     def _default_clean(self, value):
@@ -66,7 +72,9 @@ class Property(object):
         return value
 
     def __call__(self, value=None):
-        if value is not None:
+        """Used by ListProperty to handle lists that have been defined with
+        either a class or an instance.
+        """
         return value
 
 
@@ -76,11 +84,7 @@ class ListProperty(Property):
         """
         Contained should be a function which returns an object from the value.
         """
-        if contained == StringProperty:
-            self.contained = StringProperty().string_type
-        elif contained == BooleanProperty:
-            self.contained = bool
-        elif inspect.isclass(contained) and issubclass(contained, Property):
+        if inspect.isclass(contained) and issubclass(contained, Property):
             # If it's a class and not an instance, instantiate it so that
             # clean() can be called on it, and ListProperty.clean() will
             # use __call__ when it appends the item.
@@ -191,7 +195,7 @@ class TimestampProperty(Property):
                 return value
             else:
                 # Add a time component
-                return dt.datetime.combine(value, dt.time(), tzinfo=pytz.timezone('US/Eastern'))
+                return dt.datetime.combine(value, dt.time(), tzinfo=pytz.utc)
 
         # value isn't a date or datetime object so assume it's a string
         try: