From 62a152e4a2a5767d20edd637e9b02fb1b095d66f Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Tue, 9 Feb 2021 14:13:18 -0500
Subject: [PATCH] get version number from package version instead of rewriting
 the __init__.py file

---
 python/install.py         | 33 +--------------------------------
 python/lammps/__init__.py | 35 +++++++++++++++++++++++++++++++++--
 2 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/python/install.py b/python/install.py
index bd0874593f..6765c33925 100644
--- a/python/install.py
+++ b/python/install.py
@@ -10,7 +10,7 @@ build target in the conventional and CMake based build systems
 # copy LAMMPS shared library and lammps package to system dirs
 
 from __future__ import print_function
-import sys,os,re,shutil
+import sys,os,shutil
 from argparse import ArgumentParser
 
 parser = ArgumentParser(prog='install.py',
@@ -90,35 +90,11 @@ def get_lammps_version(header):
 
 verstr = get_lammps_version(args.version)
 
-# convert string version to numeric version
-vernum = 0
-vregex = re.compile(r"([0-9]+)([A-Za-z]+)(2[0-9]+)")
-m = vregex.match(verstr)
-if (m):
-    month2num = { 'Jan' : 1, 'Feb' : 2, 'Mar' : 3, 'Apr' : 4, 'May' : 5, 'Jun' : 6,
-            'Jul' : 7, 'Aug' : 8, 'Sep' : 9, 'Oct' : 10, 'Nov' : 11, 'Dec' : 12 }
-    try:
-      vernum = int(m.group(3))*10000
-      vernum += month2num[m.group(2)]*100
-      vernum += int(m.group(1))
-    except:
-      exit('Failure to parse version string: %s' % verstr)
-
 print("Installing LAMMPS Python package version %s into site-packages folder" % verstr)
 
 # we need to switch to the folder of the python package
 os.chdir(os.path.dirname(args.package))
 
-
-
-# update version number in lammps module
-vregex = re.compile(r".*(__version__ += +)[0-9]+")
-with open(os.path.join('lammps','__init__.py'), "r+") as f:
-    content = f.read()
-    f.seek(0)
-    f.write(re.sub(vregex, lambda match: '{}{}'.format(match.group(1), vernum), content))
-    f.truncate()
-
 from distutils.core import setup
 from distutils.sysconfig import get_python_lib
 import site
@@ -150,10 +126,3 @@ if tryuser:
     setup(**setup_kwargs)
   except:
     print("Installation into user site package folder failed.")
-
-# restore __version__ == 0 for in place usage
-with open(os.path.join('lammps','__init__.py'), "r+") as f:
-    content = f.read()
-    f.seek(0)
-    f.write(re.sub(vregex, lambda match: '{}{}'.format(match.group(1), 0), content))
-    f.truncate()
diff --git a/python/lammps/__init__.py b/python/lammps/__init__.py
index be496167e8..89ff30ead9 100644
--- a/python/lammps/__init__.py
+++ b/python/lammps/__init__.py
@@ -13,6 +13,37 @@ from .core import *
 from .data import *
 from .pylammps import *
 
-# automatically updated during installation
+# convert module string version to numeric version
+def get_version_number():
+    import re
+    from sys import version_info
+    vstring = None
+    if version_info.major == 3 and version_info.minor >= 8:
+        from importlib.metadata import version
+        try:
+            vstring = version('lammps')
+        except: pass
+    else:
+        from pkg_resources import get_distribution
+        try:
+            vstring = get_distribution('lammps').version
+        except: pass
 
-__version__ = 0
+    if not vstring:
+        return 0
+
+    vregex = re.compile(r"([0-9]+)([A-Za-z]+)(2[0-9]+)")
+    m = vregex.match(vstring)
+
+    if (m):
+        month2num = { 'Jan' : 1, 'Feb' : 2, 'Mar' : 3, 'Apr' : 4, 'May' : 5, 'Jun' : 6,
+                'Jul' : 7, 'Aug' : 8, 'Sep' : 9, 'Oct' : 10, 'Nov' : 11, 'Dec' : 12 }
+        try:
+            vernum = int(m.group(3))*10000
+            vernum += month2num[m.group(2)]*100
+            vernum += int(m.group(1))
+        except:
+            exit('Failure to parse version string: %s' % verstr)
+    return vernum
+
+__version__ = get_version_number()