Add module for Python-only version extraction.

Resolve __version__ in diffpy.srreal module without having
to import all extension modules.

This closes #5.

Author: pavoljuhas

diffpy/srreal/__init__.py

@@ -18,7 +18,7 @@
 """
 
 # package version
-from diffpy.srreal.version import __version__
+from diffpy.srreal._version_data import __version__
 
 
 # End of file

diffpy/srreal/_version_data.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python
+##############################################################################
+#
+# diffpy.srreal     by DANSE Diffraction group
+#                   Simon J. L. Billinge
+#                   (c) 2008 The Trustees of Columbia University
+#                   in the City of New York.  All rights reserved.
+#
+# File coded by:    Pavol Juhas
+#
+# See AUTHORS.txt for a list of people who contributed.
+# See LICENSE_DANSE.txt for license information.
+#
+##############################################################################
+
+
+"""Extraction of version data for diffpy.srreal package
+
+Does not import any extension module unlike the standard version.
+"""
+
+from pkg_resources import resource_filename
+from ConfigParser import RawConfigParser
+
+# obtain version information from the version.cfg file
+cp = RawConfigParser(dict(version='', date='', commit='', timestamp=0))
+if not cp.read(resource_filename(__name__, 'version.cfg')):
+    from warnings import warn
+    warn('Package metadata not found, execute "./setup.py egg_info".')
+
+__version__ = cp.get('DEFAULT', 'version')
+__date__ = cp.get('DEFAULT', 'date')
+__gitsha__ = cp.get('DEFAULT', 'commit')
+__timestamp__ = cp.getint('DEFAULT', 'timestamp')
+
+del cp
+
+# End of file

diffpy/srreal/version.py

@@ -14,24 +14,13 @@
 ##############################################################################
 
 
-"""Definition of __version__, __date__, __gitsha__, libdiffpy_version_info.
+"""Definitions of version-related constants and of libdiffpy_version_info.
 """
 
-from pkg_resources import resource_filename
-from ConfigParser import RawConfigParser
-
-# obtain version information from the version.cfg file
-cp = RawConfigParser(dict(version='', date='', commit='', timestamp=0))
-if not cp.read(resource_filename(__name__, 'version.cfg')):
-    from warnings import warn
-    warn('Package metadata not found, execute "./setup.py egg_info".')
-
-__version__ = cp.get('DEFAULT', 'version')
-__date__ = cp.get('DEFAULT', 'date')
-__gitsha__ = cp.get('DEFAULT', 'commit')
-__timestamp__ = cp.getint('DEFAULT', 'timestamp')
-
-del cp
+from diffpy.srreal._version_data import __version__
+from diffpy.srreal._version_data import __date__
+from diffpy.srreal._version_data import __gitsha__
+from diffpy.srreal._version_data import __timestamp__
 
 # version information on the active libdiffpy shared library -----------------