add helper for distribution versions

Author: RonnyPfannschmidt

apipkg.py

@@ -24,6 +24,18 @@ def _py_abspath(path):
         return os.path.abspath(path)
 
 
+def distribution_version(name):
+    """try to get the version of the named distribution,
+    returs None on failure"""
+    from pkg_resources import get_distribution, DistributionNotFound
+    try:
+        dist = get_distribution(name)
+    except DistributionNotFound:
+        pass
+    else:
+        return dist.version
+
+
 def initpkg(pkgname, exportdefs, attr=dict()):
     """ initialize given package from the export definitions. """
     oldmod = sys.modules.get(pkgname)

test_apipkg.py

@@ -526,3 +526,8 @@ def test_initpkg_without_old_module():
                    dict(modules="sys:modules"))
     from initpkg_without_old_module import modules
     assert modules is sys.modules
+
+
+def test_get_distribution_version():
+    assert apipkg.distribution_version('setuptools') is not None
+    assert apipkg.distribution_version('email') is None