[chore] setup a proper version number (#20)

CHANGELOG.md

+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.0.0] - 2020-07-31
+
+- Initial release.

fairscale/__init__.py

@@ -3,6 +3,8 @@
 # This source code is licensed under the BSD license found in the
 # LICENSE file in the root directory of this source tree.
 
+__version__ = "0.0.0"
+
 ################################################################################
 # Import most common subpackages
 ################################################################################

setup.py

@@ -3,6 +3,7 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
 import os
+import re
 import warnings
 
 import setuptools
@@ -16,6 +17,15 @@ def fetch_requirements():
     return reqs
 
 
+# https://packaging.python.org/guides/single-sourcing-package-version/
+def find_version(version_file_path):
+    with open(version_file_path) as version_file:
+        version_match = re.search(r"^__version__ = ['\"]([^'\"]*)['\"]", version_file.read(), re.M)
+        if version_match:
+            return version_match.group(1)
+        raise RuntimeError("Unable to find version string.")
+
+
 extensions = []
 cmdclass = {}
 
@@ -43,6 +53,7 @@ if __name__ == "__main__":
     setuptools.setup(
         name="fairscale",
         description="fairscale: Utility library for large-scale and high-performance training.",
+        version=find_version("fairscale/__init__.py"),
         install_requires=fetch_requirements(),
         include_package_data=True,
         packages=setuptools.find_packages(exclude=("tests", "tests.*")),