Moving set_default_dataset_id to _implicit_environ module.

Also splitting out behavior into a get_default_dataset_id method
and then the set_default_dataset_id around in.

gcloud/datastore/__init__.py

@@ -46,10 +46,9 @@
   when race conditions may occur.
 """
 
-import os
-
 from gcloud import credentials
 from gcloud.datastore import _implicit_environ
+from gcloud.datastore._implicit_environ import set_default_dataset_id
 from gcloud.datastore.api import allocate_ids
 from gcloud.datastore.api import delete
 from gcloud.datastore.api import get
@@ -66,37 +65,6 @@
          'https://www.googleapis.com/auth/userinfo.email')
 """The scopes required for authenticating as a Cloud Datastore consumer."""
 
-_DATASET_ENV_VAR_NAME = 'GCLOUD_DATASET_ID'
-
-
-def set_default_dataset_id(dataset_id=None):
-    """Set default dataset ID either explicitly or implicitly as fall-back.
-
-    In implicit case, supports three cases. In order of precedence, the
-    implicit cases are:
-    - GCLOUD_DATASET_ID environment variable
-    - Google App Engine application ID
-    - Google Compute Engine project ID (from metadata server)
-
-    :type dataset_id: string
-    :param dataset_id: Optional. The dataset ID to use as default.
-
-    :raises: :class:`EnvironmentError` if no dataset ID was implied.
-    """
-    if dataset_id is None:
-        dataset_id = os.getenv(_DATASET_ENV_VAR_NAME)
-
-    if dataset_id is None:
-        dataset_id = _implicit_environ.app_engine_id()
-
-    if dataset_id is None:
-        dataset_id = _implicit_environ.compute_engine_id()
-
-    if dataset_id is not None:
-        _implicit_environ.DEFAULT_ENVIRON.dataset_id = dataset_id
-    else:
-        raise EnvironmentError('No dataset ID could be inferred.')
-
 
 def set_default_connection(connection=None):
     """Set default connection either explicitly or implicitly as fall-back.

gcloud/datastore/_implicit_environ.py

@@ -12,12 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""Module to provide implicit behavior based on enviroment.
+"""Module to provide implicit behavior based on environment.
 
 Acts as a mutable namespace to allow the datastore package to
-imply the current dataset ID and connection from the enviroment.
+imply the current dataset ID and connection from the environment.
 """
 
+import os
 import socket
 
 from six.moves.http_client import HTTPConnection  # pylint: disable=F0401
@@ -28,14 +29,17 @@
     app_identity = None
 
 
-class Enviroment(object):
+_DATASET_ENV_VAR_NAME = 'GCLOUD_DATASET_ID'
+
+
+class Environment(object):
     """Container for environment settings."""
 
     dataset_id = None
-    """Attribute to allow persistent implied dataset ID from enviroment."""
+    """Attribute to allow persistent implied dataset ID from environment."""
 
     connection = None
-    """Attribute to allow persistent implied connection from enviroment."""
+    """Attribute to allow persistent implied connection from environment."""
 
 
 def app_engine_id():
@@ -84,4 +88,53 @@ def compute_engine_id():
         connection.close()
 
 
-DEFAULT_ENVIRON = Enviroment()
+def get_default_dataset_id(dataset_id=None):
+    """Get default dataset ID either explicitly or implicitly as fall-back.
+
+    In implicit case, supports three cases. In order of precedence, the
+    implicit cases are:
+    - GCLOUD_DATASET_ID environment variable
+    - Google App Engine application ID
+    - Google Compute Engine project ID (from metadata server)
+
+    :type dataset_id: string
+    :param dataset_id: Optional. The dataset ID to use as default.
+
+    :rtype: string or ``NoneType``
+    :returns: The inferred dataset or None.
+    """
+    if dataset_id is None:
+        dataset_id = os.getenv(_DATASET_ENV_VAR_NAME)
+
+    if dataset_id is None:
+        dataset_id = app_engine_id()
+
+    if dataset_id is None:
+        dataset_id = compute_engine_id()
+
+    return dataset_id
+
+
+def set_default_dataset_id(dataset_id=None):
+    """Set default dataset ID either explicitly or implicitly as fall-back.
+
+    In implicit case, supports three cases. In order of precedence, the
+    implicit cases are:
+    - GCLOUD_DATASET_ID environment variable
+    - Google App Engine application ID
+    - Google Compute Engine project ID (from metadata server)
+
+    :type dataset_id: string
+    :param dataset_id: Optional. The dataset ID to use as default.
+
+    :raises: :class:`EnvironmentError` if no dataset ID was implied.
+    """
+    dataset_id = get_default_dataset_id(dataset_id=dataset_id)
+
+    if dataset_id is not None:
+        DEFAULT_ENVIRON.dataset_id = dataset_id
+    else:
+        raise EnvironmentError('No dataset ID could be inferred.')
+
+
+DEFAULT_ENVIRON = Environment()