cfg: convert types automatically based on default values

The type of the config value is string by default and we need to cast it to the
appropriate type - it is error-prone.

The swift3 middleware actually knows the correct config type from the default
value in swift3.cfg and there is no need to convert it manually.

Change-Id: I28761ed12c3bdd85cb2a80048d2abc0dd23222b3

swift3/cfg.py

@@ -13,9 +13,33 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from swift.common.utils import config_true_value
+
+
+class Config(dict):
+    def __init__(self, base=None):
+        if base is not None:
+            self.update(base)
+
+    def update(self, other):
+        if hasattr(other, 'keys'):
+            for key in other.keys():
+                self[key] = other[key]
+        else:
+            for key, value in other:
+                self[key] = value
+
+    def __setitem__(self, key, value):
+        if isinstance(self.get(key), bool):
+            dict.__setitem__(self, key, config_true_value(value))
+        elif isinstance(self.get(key), int):
+            dict.__setitem__(self, key, int(value))
+        else:
+            dict.__setitem__(self, key, value)
+
 # Global config dictionary.  The default values can be defined here.
-CONF = {
+CONF = Config({
     'location': 'US',
     'max_bucket_listing': 1000,
     'storage_domain': '',
-}
+})

swift3/controllers/bucket.py

@@ -51,7 +51,7 @@ class BucketController(Controller):
                 raise InvalidArgument('max-keys', req.params['max-keys'])
 
         max_keys = int(req.params.get('max-keys', CONF['max_bucket_listing']))
-        max_keys = min(max_keys, int(CONF['max_bucket_listing']))
+        max_keys = min(max_keys, CONF['max_bucket_listing'])
 
         query = {
             'format': 'json',

swift3/test/unit/test_cfg.py

@@ -0,0 +1,43 @@
+# Copyright (c) 2014 OpenStack Foundation
+#
+# Licensed 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.
+
+import unittest
+
+from swift3.cfg import Config
+
+class TestSwift3Cfg(unittest.TestCase):
+    def test_config(self):
+        conf = Config(
+            {
+                'a': 'str',
+                'b': 10,
+                'c': True,
+            }
+        )
+
+        conf.update(
+            {
+                'a': 'str2',
+                'b': '100',
+                'c': 'false',
+            }
+        )
+
+        self.assertEquals(conf['a'], 'str2')
+        self.assertEquals(conf['b'], 100)
+        self.assertEquals(conf['c'], False)
+
+if __name__ == '__main__':
+    unittest.main()