Update MultiplexedPath to expect Traversable and add a compatibility shim with deprecation warning.

Author: jaraco

importlib_resources/_compat.py

@@ -4,6 +4,7 @@
 import os
 import sys
 import pathlib
+import warnings
 from contextlib import suppress
 from typing import Union
 
@@ -107,3 +108,19 @@ def wrap_spec(package):
 else:
     # PathLike is only subscriptable at runtime in 3.9+
     StrPath = Union[str, "os.PathLike[str]"]
+
+
+def ensure_traversable(path):
+    """
+    Convert deprecated string arguments to traversables (pathlib.Path).
+    """
+    if not isinstance(path, str):
+        return path
+
+    warnings.warn(
+        "String arguments are deprecated. Pass a Traversable instead.",
+        DeprecationWarning,
+        stacklevel=3,
+    )
+
+    return pathlib.Path(path)

importlib_resources/readers.py

@@ -6,7 +6,7 @@
 from . import abc
 
 from ._itertools import only
-from ._compat import ZipPath
+from ._compat import ZipPath, ensure_traversable
 
 
 def remove_duplicates(items):
@@ -62,7 +62,7 @@ class MultiplexedPath(abc.Traversable):
     """
 
     def __init__(self, *paths):
-        self._paths = list(map(pathlib.Path, remove_duplicates(paths)))
+        self._paths = list(map(ensure_traversable, remove_duplicates(paths)))
         if not self._paths:
             message = 'MultiplexedPath must contain at least one path'
             raise FileNotFoundError(message)