Update check_type calls to accept both str and os.PathLike objects. (#3618)

Co-authored-by: Paul Romano <paul.k.romano@gmail.com>

openmc/checkvalue.py

@@ -37,7 +37,7 @@ def check_type(name, value, expected_type, expected_iter_type=None, *, none_ok=F
                       [t.__name__ for t in expected_type]))
         else:
             msg = (f'Unable to set "{name}" to "{value}" which is not of type "'
-                   f'{expected_type.__name__}"')
+                   f'{expected_type}"')
         raise TypeError(msg)
 
     if expected_iter_type:

openmc/mgxs/library.py

@@ -10,6 +10,7 @@ import numpy as np
 import openmc
 import openmc.mgxs
 import openmc.checkvalue as cv
+from openmc.checkvalue import PathLike
 from ..tallies import ESTIMATOR_TYPES
 
 
@@ -851,7 +852,7 @@ class Library:
                   'since a statepoint has not yet been loaded'
             raise ValueError(msg)
 
-        cv.check_type('filename', filename, str)
+        cv.check_type('filename', filename, (str, PathLike))
         cv.check_type('directory', directory, str)
 
         import h5py
@@ -894,7 +895,7 @@ class Library:
 
         """
 
-        cv.check_type('filename', filename, str)
+        cv.check_type('filename', filename, (str, PathLike))
         cv.check_type('directory', directory, str)
 
         # Make directory if it does not exist
@@ -930,7 +931,7 @@ class Library:
 
         """
 
-        cv.check_type('filename', filename, str)
+        cv.check_type('filename', filename, (str, PathLike))
         cv.check_type('directory', directory, str)
 
         # Make directory if it does not exist

openmc/mgxs/mdgxs.py

@@ -7,6 +7,7 @@ import numpy as np
 
 import openmc
 import openmc.checkvalue as cv
+from openmc.checkvalue import PathLike
 from openmc.mgxs import MGXS
 from .mgxs import _DOMAIN_TO_FILTER
 
@@ -722,7 +723,7 @@ class MDGXS(MGXS):
 
         """
 
-        cv.check_type('filename', filename, str)
+        cv.check_type('filename', filename, (str, PathLike))
         cv.check_type('directory', directory, str)
         cv.check_value('format', format, ['csv', 'excel', 'pickle', 'latex'])
         cv.check_value('xs_type', xs_type, ['macro', 'micro'])

openmc/mgxs/mgxs.py

@@ -10,6 +10,7 @@ import numpy as np
 import openmc
 from openmc.data import REACTION_MT, REACTION_NAME, FISSION_MTS
 import openmc.checkvalue as cv
+from openmc.checkvalue import PathLike
 from ..tallies import ESTIMATOR_TYPES
 from . import EnergyGroups
 
@@ -1982,7 +1983,7 @@ class MGXS:
 
         """
 
-        cv.check_type('filename', filename, str)
+        cv.check_type('filename', filename, (str, PathLike))
         cv.check_type('directory', directory, str)
         cv.check_value('format', format, ['csv', 'excel', 'pickle', 'latex'])
         cv.check_value('xs_type', xs_type, ['macro', 'micro'])

openmc/mgxs_library.py

@@ -2514,8 +2514,7 @@ class MGXSLibrary:
 
         """
 
-        check_type('filename', filename, PathLike)
-
+        check_type('filename', filename, (str, PathLike))
         # Create and write to the HDF5 file
         file = h5py.File(filename, "w", libver=libver)
         file.attrs['filetype'] = np.bytes_(_FILETYPE_MGXS_LIBRARY)
@@ -2554,7 +2553,7 @@ class MGXSLibrary:
             raise ValueError("Either path or openmc.config['mg_cross_sections']"
                              "must be set")
 
-        check_type('filename', filename, str)
+        check_type('filename', filename, (str, PathLike))
         file = h5py.File(filename, 'r')
 
         # Check filetype and version

openmc/plots.py

@@ -439,7 +439,7 @@ class PlotBase(IDManagerMixin):
 
     @filename.setter
     def filename(self, filename):
-        cv.check_type('filename', filename, str)
+        cv.check_type('filename', filename, (str, PathLike))
         self._filename = filename
 
     @property

tests/unit_tests/test_pathlike_simple.py

@@ -0,0 +1,46 @@
+"""Simple test for PathLike filename support"""
+
+from pathlib import Path
+
+import pytest
+import openmc
+from openmc.checkvalue import check_type, PathLike
+
+
+def test_pathlike_type_checking():
+    """Test that PathLike type checking works correctly"""
+
+    # Test with string (should work)
+    check_type('filename', 'test.txt', PathLike)
+
+    # Test with Path object (should work)
+    path_obj = Path('test.txt')
+    check_type('filename', path_obj, PathLike)
+
+    # Test with Path object containing subdirectories (should work)
+    path_with_subdir = Path('subdir') / 'test.txt'
+    check_type('filename', path_with_subdir, PathLike)
+
+    # Test with invalid type (should raise TypeError)
+    with pytest.raises(TypeError):
+        check_type('filename', 123, PathLike)
+
+
+def test_plot_filename_pathlike():
+    """Test that plot filename accepts Path objects"""
+
+    plot = openmc.Plot()
+
+    # Test with string (should still work)
+    plot.filename = "test_plot"
+    assert plot.filename == "test_plot"
+
+    # Test with Path object
+    path_obj = Path("test_plot_path")
+    plot.filename = path_obj
+    assert plot.filename == path_obj
+
+    # Test with Path object containing subdirectories
+    path_with_subdir = Path("subdir") / "test_plot"
+    plot.filename = path_with_subdir
+    assert plot.filename == path_with_subdir