1 files changed, 58 insertions, 0 deletions
diff --git a/dev-python/astropy/files/astropy-ply.py b/dev-python/astropy/files/astropy-ply.py
new file mode 100644
index 000000000000..19eb104c4ca0
--- /dev/null
+++ b/dev-python/astropy/files/astropy-ply.py
@@ -0,0 +1,58 @@
+# Licensed under a 3-clause BSD style license - see LICENSE.rst
+
+"""
+Handle loading ply package from system or from the bundled copy
+"""
+
+import imp
+from distutils.version import StrictVersion
+
+
+def _find_module(name, path=None):
+    """
+    Alternative to `imp.find_module` that can also search in subpackages.
+    """
+
+    parts = name.split('.')
+
+    for part in parts:
+        if path is not None:
+            path = [path]
+
+        fh, path, descr = imp.find_module(part, path)
+
+    return fh, path, descr
+
+_PLY_MIN_VERSION = StrictVersion('3.4')
+
+# Update this to prevent Astropy from using its bundled copy of ply
+# (but only if some other version of at least _PLY_MIN_VERSION can
+# be provided)
+_PLY_SEARCH_PATH = ['ply']
+
+
+for mod_name in _PLY_SEARCH_PATH:
+    try:
+        mod_info = _find_module(mod_name)
+        #mod_lex_info = _find_module(mod_name + '.lex')
+    except ImportError:
+        continue
+
+    mod = imp.load_module(__name__, *mod_info)
+    #mod_lex = imp.load_module(__name__ + '.lex', *mod_lex_info)
+
+    try:
+    #    if StrictVersion(mod_lex.__version__) >= _PLY_MIN_VERSION:
+    #        break
+        break
+    except (AttributeError, ValueError):
+        # Attribute error if the ply module isn't what it should be and doesn't
+        # have a .__version__; ValueError if the version string exists but is
+        # somehow bogus/unparseable
+        continue
+else:
+    raise ImportError(
+        "Astropy requires the 'ply' module of minimum version {0}; "
+        "normally this is bundled with the astropy package so if you get "
+        "this warning consult the packager of your Astropy "
+        "distribution.".format(_PLY_MIN_VERSION))