Change the way version info is handled in packaging (unitaryfund#247)

* Add .python-version to .gitignore for pyenv

* Add VERSION.txt to MANIFEST.in so it can be used in packaging

* Add version.py file that gets overwritten when packaging

* Overwrite and restore version.py in setup.py

* Import from version.py in __init__.py rather than parsing VERSION.txt

.gitignore

@@ -1,5 +1,6 @@
 .DS_Store
 .vscode
+.python-version
 .idea/
 .coverage*
 *.dat

MANIFEST.in

@@ -1,5 +1,6 @@
-include README.md
 include LICENSE
+include README.md
+include VERSION.txt
 include requirements.txt
 include development_requirements.txt
 include test_build.sh

mitiq/__init__.py

@@ -3,6 +3,8 @@
 This is the top level module from which functions and classes of
 Mitiq can be directly imported.
 """
+from mitiq.version import __version__
+
 import os
 from typing import Union
 
@@ -32,11 +34,6 @@
 # this must be after QPROGRAM as the zne.py module imports QPROGRAM
 from mitiq.zne import execute_with_zne, mitigate_executor
 
-_directory_of_this_file = os.path.dirname(os.path.abspath(__file__))
-
-with open(str(_directory_of_this_file) + "/../VERSION.txt", "r") as f:
-    __version__ = f.read().strip()
-
 
 def version():
     """Returns the Mitiq version number."""

mitiq/version.py

@@ -0,0 +1,9 @@
+"""
+NOTE: This file will be overwritten by the packaging process.
+"""
+import os
+
+directory_of_this_file = os.path.dirname(os.path.abspath(__file__))
+
+with open(f"{directory_of_this_file}/../VERSION.txt", "r") as f:
+    __version__ = f.read().strip()

setup.py

@@ -9,6 +9,14 @@
 with open('development_requirements.txt') as f:
     dev_requirements = f.read().splitlines()
 
+# save the source code in version.py
+with open("mitiq/version.py", "r") as f:
+    version_file_source = f.read()
+
+# overwrite version.py in the source distribution
+with open("mitiq/version.py", "w") as f:
+    f.write(f"__version__ = '{__version__}'\n")
+
 setup(
     name='mitiq',
     version=__version__,
@@ -35,3 +43,7 @@
      url = "https://unitary.fund",
 
 )
+
+# restore version.py to its previous state
+with open("mitiq/version.py", "w") as f:
+    f.write(version_file_source)