fix: avoid using 'pkg_resources' to determine version (#40)

Closes #39.

google/cloud/_http.py

@@ -19,19 +19,19 @@
 import platform
 import warnings
 
-from pkg_resources import get_distribution
 from six.moves import collections_abc
 from six.moves.urllib.parse import urlencode
 
 from google.api_core.client_info import ClientInfo
 from google.cloud import exceptions
+from google.cloud import version
 
 
 API_BASE_URL = "https://www.googleapis.com"
 """The base of the API call URL."""
 
 DEFAULT_USER_AGENT = "gcloud-python/{0}".format(
-    get_distribution("google-cloud-core").version
+    version.__version__
 )
 """The user agent for google-cloud-python requests."""
 

google/cloud/version.py

@@ -0,0 +1,15 @@
+# Copyright 2020 Google LLC
+#
+# 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.
+
+__version__ = "1.4.2"

setup.py

@@ -22,7 +22,6 @@
 
 name = "google-cloud-core"
 description = "Google Cloud API client core library"
-version = "1.4.2"
 # Should be one of:
 # 'Development Status :: 3 - Alpha'
 # 'Development Status :: 4 - Beta'
@@ -36,6 +35,11 @@
 
 package_root = os.path.abspath(os.path.dirname(__file__))
 
+version = {}
+with open(os.path.join(package_root, "google/cloud/version.py")) as fp:
+    exec(fp.read(), version)
+version = version['__version__']
+
 readme_filename = os.path.join(package_root, "README.rst")
 with io.open(readme_filename, encoding="utf-8") as readme_file:
     readme = readme_file.read()