Adding methods for default / implicit behavior in storage.

Addresses part of googleapis#337.

gcloud/datastore/_implicit_environ.py

@@ -1,3 +1,17 @@
+# Copyright 2014 Google Inc. All rights reserved.
+#
+# 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.
+
 """Module to provide implicit behavior based on enviroment.
 
 Acts as a mutable namespace to allow the datastore package to

gcloud/storage/__init__.py

@@ -37,14 +37,95 @@
   machine).
 """
 
+import os
+
 from gcloud import credentials
+from gcloud.storage import _implicit_environ
 from gcloud.storage.connection import Connection
 
 
 SCOPE = ('https://www.googleapis.com/auth/devstorage.full_control',
          'https://www.googleapis.com/auth/devstorage.read_only',
          'https://www.googleapis.com/auth/devstorage.read_write')
 
+_BUCKET_ENV_VAR_NAME = 'GCLOUD_BUCKET_NAME'
+_PROJECT_ENV_VAR_NAME = 'GCLOUD_PROJECT'
+
+
+def set_default_bucket_name(bucket_name=None):
+    """Set default bucket name either explicitly or implicitly as fall-back.
+
+    In implicit case, currently only supports enviroment variable but will
+    support App Engine, Compute Engine and other environments in the future.
+
+    Local environment variable used is:
+    - GCLOUD_BUCKET_NAME
+
+    :type bucket_name: string
+    :param bucket_name: Optional. The bucket name to use as default.
+    """
+    if bucket_name is None:
+        bucket_name = os.getenv(_BUCKET_ENV_VAR_NAME)
+
+    if bucket_name is not None:
+        _implicit_environ.BUCKET_NAME = bucket_name
+
+
+def set_default_project(project=None):
+    """Set default bucket name either explicitly or implicitly as fall-back.
+
+    In implicit case, currently only supports enviroment variable but will
+    support App Engine, Compute Engine and other environments in the future.
+
+    Local environment variable used is:
+    - GCLOUD_PROJECT
+
+    :type project: string
+    :param project: Optional. The project name to use as default.
+    """
+    if project is None:
+        project = os.getenv(_PROJECT_ENV_VAR_NAME)
+
+    if project is not None:
+        _implicit_environ.PROJECT = project
+
+
+def set_default_connection(project=None, connection=None):
+    """Set default connection either explicitly or implicitly as fall-back.
+
+    :type project: string
+    :param project: Optional. The name of the project to connect to.
+
+    :type connection: :class:`gcloud.datastore.connection.Connection`
+    :param connection: A connection provided to be the default.
+    """
+    if project is None:
+        project = _implicit_environ.PROJECT
+
+    connection = connection or get_connection(project)
+    _implicit_environ.CONNECTION = connection
+
+
+def set_defaults(bucket_name=None, project=None, connection=None):
+    """Set defaults either explicitly or implicitly as fall-back.
+
+    Uses the arguments to call the individual default methods.
+
+    :type bucket_name: string
+    :param bucket_name: Optional. The bucket name to use as default.
+
+    :type project: string
+    :param project: Optional. The name of the project to connect to.
+
+    :type connection: :class:`gcloud.datastore.connection.Connection`
+    :param connection: A connection provided to be the default.
+    """
+    set_default_bucket_name(bucket_name=bucket_name)
+    # NOTE: `set_default_project` is called before `set_default_connection`
+    #       since `set_default_connection` falls back to implicit project.
+    set_default_project(project=project)
+    set_default_connection(project=project, connection=connection)
+
 
 def get_connection(project):
     """Shortcut method to establish a connection to Cloud Storage.

gcloud/storage/_implicit_environ.py

@@ -0,0 +1,29 @@
+# Copyright 2015 Google Inc. All rights reserved.
+#
+# 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.
+
+"""Module to provide implicit behavior based on enviroment.
+
+Acts as a mutable namespace to allow the datastore package to
+imply the current dataset ID and connection from the enviroment.
+"""
+
+
+PROJECT = None
+"""Module global to allow persistent implied project from enviroment."""
+
+BUCKET_NAME = None
+"""Module global to allow persistent implied bucket name from enviroment."""
+
+CONNECTION = None
+"""Module global to allow persistent implied connection from enviroment."""