Add compatibility with pathlib.Path to python readers (#699)

* add compatibility with pathlib.Path to root_io

* outsource TypeError handling to os.fspath

* add pathlib compatibility in sio_io as well

* sio_io: only store first path in list returned by convert_to_str_paths

* make ruff import sorting happy

* outsource convert_to_str_paths

* Fix imports to be absolute

* Add module docstring to fix pylint complaints

python/podio/root_io.py

@@ -8,6 +8,7 @@
 
 from podio.base_reader import BaseReaderMixin  # pylint: disable=wrong-import-position # noqa: E402
 from podio.base_writer import BaseWriterMixin  # pylint: disable=wrong-import-position # noqa: E402
+from podio.utils import convert_to_str_paths  # pylint: disable=wrong-import-position # noqa: E402
 
 
 class Reader(BaseReaderMixin):
@@ -17,11 +18,9 @@ def __init__(self, filenames):
         """Create a reader that reads from the passed file(s).
 
         Args:
-            filenames (str or list[str]): file(s) to open and read data from
+            filenames (str or list[str] or Path or list[Path]): file(s) to open and read data from
         """
-        if isinstance(filenames, str):
-            filenames = (filenames,)
-
+        filenames = convert_to_str_paths(filenames)
         self._reader = podio.ROOTReader()
         self._reader.openFiles(filenames)
 
@@ -35,11 +34,9 @@ def __init__(self, filenames):
         """Create an RNTuple reader that reads from the passed file(s).
 
         Args:
-            filenames (str or list[str]): file(s) to open and read data from
+            filenames (str or list[str] or Path or list[Path]): file(s) to open and read data from
         """
-        if isinstance(filenames, str):
-            filenames = (filenames,)
-
+        filenames = convert_to_str_paths(filenames)
         self._reader = podio.RNTupleReader()
         self._reader.openFiles(filenames)
 
@@ -57,11 +54,9 @@ def __init__(self, filenames):
         """Create a reader that reads from the passed file(s).
 
         Args:
-            filenames (str or list[str]): file(s) to open and read data from
+            filenames (str or list[str] or Path or list[Path]): file(s) to open and read data from
         """
-        if isinstance(filenames, str):
-            filenames = (filenames,)
-
+        filenames = convert_to_str_paths(filenames)
         self._reader = podio.ROOTLegacyReader()
         self._reader.openFiles(filenames)
         self._is_legacy = True
@@ -76,8 +71,9 @@ def __init__(self, filename):
         """Create a writer for writing files
 
         Args:
-            filename (str): The name of the output file
+            filename (str or Path): The name of the output file
         """
+        filename = convert_to_str_paths(filename)[0]
         self._writer = podio.ROOTWriter(filename)
         super().__init__()
 
@@ -89,7 +85,8 @@ def __init__(self, filename):
         """Create a writer for writing files
 
         Args:
-            filename (str): The name of the output file
+            filename (str or Path): The name of the output file
         """
+        filename = convert_to_str_paths(filename)[0]
         self._writer = podio.RNTupleWriter(filename)
         super().__init__()

python/podio/sio_io.py

@@ -11,6 +11,7 @@
 
 from podio.base_reader import BaseReaderMixin  # pylint: disable=wrong-import-position
 from podio.base_writer import BaseWriterMixin  # pylint: disable=wrong-import-position
+from podio.utils import convert_to_str_paths  # pylint: disable=wrong-import-position # noqa: E402
 
 
 class Reader(BaseReaderMixin):
@@ -20,8 +21,9 @@ def __init__(self, filename):
         """Create a reader that reads from the passed file.
 
         Args:
-            filename (str): File to open and read data from
+            filename (str or Path): File to open and read data from.
         """
+        filename = convert_to_str_paths(filename)[0]
         self._reader = podio.SIOReader()
         self._reader.openFile(filename)
 
@@ -39,8 +41,9 @@ def __init__(self, filename):
         """Create a reader that reads from the passed file.
 
         Args:
-            filename (str): File to open and read data from
+            filename (str or Path): File to open and read data from.
         """
+        filename = convert_to_str_paths(filename)[0]
         self._reader = podio.SIOLegacyReader()
         self._reader.openFile(filename)
         self._is_legacy = True
@@ -49,13 +52,15 @@ def __init__(self, filename):
 
 
 class Writer(BaseWriterMixin):
-    """Writer class for writing podio root files"""
+    """Writer class for writing podio root files."""
 
     def __init__(self, filename):
-        """Create a writer for writing files
+        """Create a writer for writing files.
 
         Args:
-            filename (str): The name of the output file
+            filename (str or Path): The name of the output file.
         """
+        filename = convert_to_str_paths(filename)[0]
         self._writer = podio.SIOWriter(filename)
+
         super().__init__()

python/podio/utils.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python3
+"""utility functionality for podio"""
+
+import os
+from collections.abc import Iterable
+from pathlib import Path
+
+
+def convert_to_str_paths(filenames):
+    """Converts filenames to string paths, handling both string and pathlib.Path objects and
+       iterables of such objects.
+
+    Args:
+        filenames (str, Path, or Iterable[str | Path]): A single filepath or an iterable of
+        filepaths to convert to str object(s).
+
+    Returns:
+        list[str]: A list of filepaths as strings.
+    """
+
+    if isinstance(filenames, Iterable) and not isinstance(filenames, (str, Path)):
+        return [os.fspath(fn) for fn in filenames]
+
+    return [os.fspath(filenames)]