ENH: Accept pathlib.Path objects where filenames are accepted

nibabel/filebasedimages.py

@@ -12,7 +12,7 @@
 from copy import deepcopy
 from .fileholders import FileHolder
 from .filename_parser import (types_filenames, TypesFilenamesError,
-                              splitext_addext)
+                              splitext_addext, _stringify_path)
 from .openers import ImageOpener
 from .deprecated import deprecate_with_version
 
@@ -252,10 +252,12 @@ def set_filename(self, filename):
            ``.file_map`` attribute. Otherwise, the image instance will
            try and guess the other filenames from this given filename.
         '''
+        filename = _stringify_path(filename)
         self.file_map = self.__class__.filespec_to_file_map(filename)
 
     @classmethod
     def from_filename(klass, filename):
+        filename = _stringify_path(filename)
         file_map = klass.filespec_to_file_map(filename)
         return klass.from_file_map(file_map)
 
@@ -330,6 +332,7 @@ def to_filename(self, filename):
         -------
         None
         '''
+        filename = _stringify_path(filename)
         self.file_map = self.filespec_to_file_map(filename)
         self.to_file_map()
 

nibabel/filename_parser.py

@@ -14,11 +14,41 @@
 except NameError:
     basestring = str
 
+import pathlib
+
 
 class TypesFilenamesError(Exception):
     pass
 
 
+def _stringify_path(filepath_or_buffer):
+    """Attempt to convert a path-like object to a string.
+
+    Parameters
+    ----------
+    filepath_or_buffer : object to be converted
+    Returns
+    -------
+    str_filepath_or_buffer : maybe a string version of the object
+    Notes
+    -----
+    Objects supporting the fspath protocol (python 3.6+) are coerced
+    according to its __fspath__ method.
+    For backwards compatibility with older pythons, pathlib.Path and
+    py.path objects are specially coerced.
+    Any other object is passed through unchanged, which includes bytes,
+    strings, buffers, or anything else that's not even path-like.
+
+    Copied from:
+    https://github.com/pandas-dev/pandas/blob/325dd686de1589c17731cf93b649ed5ccb5a99b4/pandas/io/common.py#L131-L160
+    """
+    if hasattr(filepath_or_buffer, "__fspath__"):
+        return filepath_or_buffer.__fspath__()
+    elif isinstance(filepath_or_buffer, pathlib.Path):
+        return str(filepath_or_buffer)
+    return filepath_or_buffer
+
+
 def types_filenames(template_fname, types_exts,
                     trailing_suffixes=('.gz', '.bz2'),
                     enforce_extensions=True,
@@ -190,6 +220,8 @@ def parse_filename(filename,
     >>> parse_filename('/path/fnameext2.gz', types_exts, ('.gz',))
     ('/path/fname', 'ext2', '.gz', 't2')
     '''
+    filename = _stringify_path(filename)
+
     ignored = None
     if match_case:
         endswith = _endswith
@@ -257,6 +289,8 @@ def splitext_addext(filename,
     >>> splitext_addext('fname.ext.foo', ('.foo', '.bar'))
     ('fname', '.ext', '.foo')
     '''
+    filename = _stringify_path(filename)
+
     if match_case:
         endswith = _endswith
     else:

nibabel/loadsave.py

@@ -12,7 +12,7 @@
 import os
 import numpy as np
 
-from .filename_parser import splitext_addext
+from .filename_parser import splitext_addext, _stringify_path
 from .openers import ImageOpener
 from .filebasedimages import ImageFileError
 from .imageclasses import all_image_classes
@@ -35,12 +35,16 @@ def load(filename, **kwargs):
     img : ``SpatialImage``
        Image of guessed type
     '''
+    filename = _stringify_path(filename)
+
+    # Check file exists and is not empty
     try:
         stat_result = os.stat(filename)
     except OSError:
         raise FileNotFoundError("No such file or no access: '%s'" % filename)
     if stat_result.st_size <= 0:
         raise ImageFileError("Empty file: '%s'" % filename)
+
     sniff = None
     for image_klass in all_image_classes:
         is_valid, sniff = image_klass.path_maybe_image(filename, sniff)
@@ -92,6 +96,7 @@ def save(img, filename):
     -------
     None
     '''
+    filename = _stringify_path(filename)
 
     # Save the type as expected
     try: