Use setuptools_scm for version numbering

.gitignore

@@ -10,7 +10,6 @@ __pycache__
 *.c
 
 # Other generated files
-*/version.py
 */cython_version.py
 htmlcov
 .coverage

astrowidgets/_astropy_init.py

@@ -1,6 +1,6 @@
 # Licensed under a 3-clause BSD style license - see LICENSE.rst
 
-__all__ = ['__version__', '__githash__']
+__all__ = ['__version__']
 
 # this indicates whether or not we are in the package's setup.py
 try:
@@ -17,11 +17,6 @@
     from .version import version as __version__
 except ImportError:
     __version__ = ''
-try:
-    from .version import githash as __githash__
-except ImportError:
-    __githash__ = ''
-
 
 if not _ASTROPY_SETUP_:  # noqa
     import os

astrowidgets/version.py

@@ -0,0 +1,12 @@
+version = 'unknown.dev'
+try:
+    from importlib_metadata import version as _version, PackageNotFoundError
+    version = _version('my-package')
+except ImportError:
+    from pkg_resources import get_distribution, DistributionNotFound
+    try:
+        version = get_distribution("my-package").version
+    except DistributionNotFound:
+        pass
+except PackageNotFoundError:
+    pass

pyproject.toml

@@ -1,4 +1,5 @@
 [build-system]
 requires = ["setuptools",
+            "setuptools_scm",
             "wheel"]
 build-backend = 'setuptools.build_meta'

setup.cfg

@@ -43,6 +43,7 @@ github_project = astropy/astrowidgets
 [options]
 zip_safe = False
 packages = find:
+setup_requires = setuptools_scm
 install_requires =
     astropy
     ginga