enh(filemanip): Solidify a patched version of pathlib.Path for internal consumption.

Author: oesteban

nipype/interfaces/base/specs.py

@@ -21,7 +21,8 @@
 
 from traits.trait_errors import TraitError
 from traits.trait_handlers import TraitDictObject, TraitListObject
-from ...utils.filemanip import md5, hash_infile, hash_timestamp, to_str
+from ...utils.filemanip import (
+    md5, hash_infile, hash_timestamp, to_str, USING_PATHLIB2)
 from .traits_extension import (
     traits,
     Undefined,
@@ -32,13 +33,6 @@
 from ... import config, __version__
 
 
-USING_PATHLIB2 = False
-try:
-    from pathlib import Path
-except ImportError:
-    from pathlib2 import Path  # noqa
-    USING_PATHLIB2 = True
-
 FLOAT_FORMAT = '{:.10f}'.format
 nipype_version = Version(__version__)
 

nipype/interfaces/base/traits_extension.py

@@ -34,10 +34,7 @@
 from traits.api import Unicode
 from future import standard_library
 
-try:
-    from pathlib import Path
-except ImportError:
-    from pathlib2 import Path
+from ...utils.filemanip import Path
 
 
 if traits_version < '3.7.0':
@@ -145,35 +142,18 @@ def validate(self, objekt, name, value, return_pathlike=False):
                 self.error(objekt, name, str(value))
 
         if self.resolve:
-            try:
-                value = value.resolve(strict=self.exists)
-            except TypeError:
-                if self.exists:
-                    value = value.resolve()
-                elif not value.is_absolute():
-                    value = Path().resolve() / value
+            value = value.resolve(strict=self.exists)
 
         if not return_pathlike and not self.pathlike:
             value = str(value)
 
         return value
 
-    # def get_value(self, objekt, name, trait=None):
-    #     value = super(BasePath, self).get_value(objekt, name)
-    #     if value is Undefined:
-    #         return self.default_value
-
-    #     if self.pathlike:
-    #         return value
-    #     return str(value)
-
 
 class Directory(BasePath):
     """
     Defines a trait whose value must be a directory path.
 
-    Examples::
-
     >>> from nipype.interfaces.base import Directory, TraitedSpec, TraitError
     >>> class A(TraitedSpec):
     ...     foo = Directory(exists=False)

nipype/utils/filemanip.py

@@ -21,7 +21,6 @@
 import contextlib
 import posixpath
 import simplejson as json
-import numpy as np
 
 from builtins import str, bytes, open
 
@@ -40,8 +39,52 @@
 
 PY3 = sys.version_info[0] >= 3
 
-class FileNotFoundError(Exception):
+
+class FileNotFoundError(OSError):
+    """Defines the expception for Python 2."""
+
+    def __init__(self, path):
+        """Initialize the exception."""
+        super(FileNotFoundError, self).__init__(
+            2, 'No such file or directory', '%s' % path)
+
+
+USING_PATHLIB2 = False
+USING_PATHLIB_PATCHED = False
+try:
+    from pathlib import Path
+except ImportError:
+    from pathlib2 import Path
+    USING_PATHLIB2 = True
+
+try:
+    Path('/invented/file/path').resolve(strict=True)
+except TypeError:
+    def _patch_resolve(self, strict=False):
+        """Add the argument strict to signature in Python>3,<3.6."""
+        resolved = Path().old_resolve() / self
+
+        if strict and not resolved.exists():
+            raise FileNotFoundError(resolved)
+        return resolved
+
+    Path.old_resolve = Path.resolve
+    Path.resolve = _patch_resolve
+    USING_PATHLIB_PATCHED = True
+except FileNotFoundError:
     pass
+except OSError:
+    def _patch_resolve(self, strict=False):
+        """Add the argument strict to signature for pathlib2."""
+        try:
+            resolved = self.old_resolve(strict=strict)
+        except OSError:
+            raise FileNotFoundError(self.old_resolve())
+
+        return resolved
+
+    Path.old_resolve = Path.resolve
+    Path.resolve = _patch_resolve
 
 
 def split_filename(fname):

nipype/utils/tests/test_filemanip.py

@@ -16,7 +16,7 @@
     check_forhash, _parse_mount_table, _cifs_table, on_cifs, copyfile,
     copyfiles, ensure_list, simplify_list, check_depends,
     split_filename, get_related_files, indirectory,
-    loadpkl, loadcrash, savepkl)
+    loadpkl, loadcrash, savepkl, FileNotFoundError, Path)
 
 
 def _ignore_atime(stat):
@@ -570,3 +570,20 @@ def test_unversioned_pklization(tmpdir):
     with pytest.raises(Exception):
         with mock.patch('nipype.utils.tests.test_filemanip.Pickled', PickledBreaker):
             loadpkl('./pickled.pkz', versioning=True)
+
+
+def test_Path_strict_resolve(tmpdir):
+    """Check the monkeypatch to test strict resolution of Path."""
+    tmpdir.chdir()
+
+    # Default strict=False should work out out of the box
+    testfile = Path('somefile.txt')
+    assert '%s/somefile.txt' % tmpdir == '%s' % testfile.resolve()
+
+    # Switching to strict=True must raise FileNotFoundError (also in Python2)
+    with pytest.raises(FileNotFoundError):
+        testfile.resolve(strict=True)
+
+    # If the file is created, it should not raise
+    testfile.write_text('')
+    assert '%s/somefile.txt' % tmpdir == '%s' % testfile.resolve(strict=True)