Both getdict and getlist return copies of the requested values

docs/topics/api.rst

@@ -252,8 +252,8 @@ Settings API
 
     .. method:: getlist(name, default=None)
 
-       Get a setting value as a list. If the setting original type is a list it
-       will be returned verbatim. If it's a string it will be split by ",".
+       Get a setting value as a list. If the setting original type is a list, a
+       copy of it will be returned. If it's a string it will be split by ",".
 
        For example, settings populated through environment variables set to
        ``'one,two'`` will return a list ['one', 'two'] when using this method.
@@ -264,6 +264,18 @@ Settings API
        :param default: the value to return if no setting is found
        :type default: any
 
+    .. method:: getdict(name, default=None)
+
+       Get a setting value as a dictionary. If the setting original type is a
+       dictionary, a copy of it will be returned. If it's a string it will
+       evaluated as a json dictionary.
+
+       :param name: the setting name
+       :type name: string
+
+       :param default: the value to return if no setting is found
+       :type default: any
+
     .. method:: copy()
 
        Make a deep copy of current settings.

scrapy/settings/__init__.py

@@ -76,23 +76,16 @@ class Settings(object):
         return float(self.get(name, default))
 
     def getlist(self, name, default=None):
-        value = self.get(name)
-        if value is None:
-            return default or []
-        elif hasattr(value, '__iter__'):
-            return value
-        else:
-            return str(value).split(',')
+        value = self.get(name, default or [])
+        if isinstance(value, six.string_types):
+            value = value.split(',')
+        return list(value)
 
     def getdict(self, name, default=None):
-        value = self.get(name)
-        if value is None:
-            return default or {}
+        value = self.get(name, default or {})
         if isinstance(value, six.string_types):
             value = json.loads(value)
-        if isinstance(value, dict):
-            return value
-        raise ValueError("Cannot convert value for setting '%s' to dict: '%s'" % (name, value))
+        return dict(value)
 
     def set(self, name, value, priority='project'):
         assert not self.frozen, "Trying to modify an immutable Settings object"