Add get_namespace method on Config object for convenient access of namespaced config options.

flask/config.py

@@ -164,5 +164,39 @@ class Config(dict):
             if key.isupper():
                 self[key] = getattr(obj, key)
 
+    def get_namespace(self, namespace, lowercase=True):
+        """Returns a dictionary containing a subset of configuration options
+        that match the specified namespace/prefix. Example usage::
+
+            app.config['IMAGE_STORE_TYPE'] = 'fs'
+            app.config['IMAGE_STORE_PATH'] = '/var/app/images'
+            app.config['IMAGE_STORE_BASE_URL'] = 'http://img.website.com'
+            image_store_config = app.config.get_namespace('IMAGE_STORE_')
+
+        The resulting dictionary `image_store` would look like::
+
+            {
+                'type': 'fs',
+                'path': '/var/app/images',
+                'base_url': 'http://img.website.com'
+            }
+
+        This is often useful when configuration options map directly to
+        keyword arguments in functions or class constructors.
+
+        :param namespace: a configuration namespace
+        :param lowercase: a flag indicating if the keys of the resulting
+                          dictionary should be lowercase
+        """
+        rv = {}
+        for k, v in self.iteritems():
+            if not k.startswith(namespace):
+                continue
+            key = k[len(namespace):]
+            if lowercase:
+                key = key.lower()
+            rv[key] = v
+        return rv
+
     def __repr__(self):
         return '<%s %s>' % (self.__class__.__name__, dict.__repr__(self))