Is this a bug in the windows tempfile.py?

[Jonathan Wright]

import tempfile
import types
print isinstance(tempfile.TemporaryFile(), types.FileType)


Prints False on Windows and True on linux or any other posix system.
The reason for the difference is on posix systems TemporaryFile returns
an actual file (the result of os.fdopen()) and on windows,
TemporaryFile returns a file wrapper which forwards getattr calls to
the underlying file.

The wrapper used on windows provides an alternative close method that
deletes the temporary file.
Should the wrapper inherit types.FileType?

Jonathan.

 

[=?ISO-8859-1?Q?=22Martin_v=2E_L=F6wis=22?=]

Should the wrapper inherit types.FileType?

No. Code assuming that the result from tempfile.TemporaryFile
is a file object is broken - you are only guaranteed a
file-like object. Applications should not use isinstance to
determine whether something is a file-like object.

Regards,
Martin