import_od: Accept os.PathLike with robust suffix handling.

Utilize the standard library's os.path.splitext() function to find the
file name suffix (case-insensitive).

Fix a [union-attr] static type check error using an empty string as
fallback for the file name on file-like objects.  The annotated TextIO
type does provide it, but mypy cannot infer that connection between
with the "read" method being available.  Failing with the ValueError
in case the attribute is missing is still better than letting out an
AttributeError.

Author: acolomb

canopen/objectdictionary/__init__.py

@@ -75,7 +75,7 @@ def export_od(
 
 
 def import_od(
-    source: Union[str, TextIO, None],
+    source: Union[str, os.PathLike, TextIO, None],
     node_id: Optional[int] = None,
 ) -> ObjectDictionary:
     """Parse an EDS, DCF, or EPF file.
@@ -92,16 +92,17 @@ def import_od(
     """
     if source is None:
         return ObjectDictionary()
-    if hasattr(source, "read"):
+    filename = ""
+    if isinstance(source, (str, os.PathLike)):
+        # Path to file
+        filename = os.fspath(source)
+    elif hasattr(source, "read"):
         # File like object
-        filename = source.name
+        filename = getattr(source, "name", "")
     elif hasattr(source, "tag"):
         # XML tree, probably from an EPF file
         filename = "od.epf"
-    else:
-        # Path to file
-        filename = source
-    suffix = filename[filename.rfind("."):].lower()
+    _, suffix = os.path.splitext(filename.lower())
     if suffix in (".eds", ".dcf"):
         from canopen.objectdictionary import eds
         return eds.import_eds(source, node_id)