To check if o
is an instance of str
or any subclass of str
, use isinstance (this would be the "canonical" way):
if isinstance(o, str):
To check if the type of o
is exactly str
(exclude subclasses):
if type(o) is str:
The following also works, and can be useful in some cases:
if issubclass(type(o), str):
See Built-in Functions in the Python Library Reference for relevant information.
One more note: in this case, if you're using Python 2, you may actually want to use:
if isinstance(o, basestring):
because this will also catch Unicode strings (unicode
is not a subclass of str
; both str
and unicode
are subclasses of basestring
). Note that basestring
no longer exists in Python 3, where there's a strict separation of strings (str
) and binary data (bytes
).
Alternatively, isinstance
accepts a tuple of classes. This will return True
if o
is an instance of any subclass of any of (str, unicode)
:
if isinstance(o, (str, unicode)):
Getting some sort of modification date in a cross-platform way is easy - just call os.path.getmtime(path)
and you'll get the Unix timestamp of when the file at path
was last modified.
Getting file creation dates, on the other hand, is fiddly and platform-dependent, differing even between the three big OSes:
- On Windows, a file's
ctime
(documented at https://msdn.microsoft.com/en-us/library/14h5k7ff.aspx) stores its creation date. You can access this in Python through os.path.getctime()
or the .st_ctime
attribute of the result of a call to os.stat()
. This won't work on Unix, where the ctime
is the last time that the file's attributes or content were changed.
- On Mac, as well as some other Unix-based OSes, you can use the
.st_birthtime
attribute of the result of a call to os.stat()
.
On Linux, this is currently impossible, at least without writing a C extension for Python. Although some file systems commonly used with Linux do store creation dates (for example, ext4
stores them in st_crtime
) , the Linux kernel offers no way of accessing them; in particular, the structs it returns from stat()
calls in C, as of the latest kernel version, don't contain any creation date fields. You can also see that the identifier st_crtime
doesn't currently feature anywhere in the Python source. At least if you're on ext4
, the data is attached to the inodes in the file system, but there's no convenient way of accessing it.
The next-best thing on Linux is to access the file's mtime
, through either os.path.getmtime()
or the .st_mtime
attribute of an os.stat()
result. This will give you the last time the file's content was modified, which may be adequate for some use cases.
Putting this all together, cross-platform code should look something like this...
import os
import platform
def creation_date(path_to_file):
"""
Try to get the date that a file was created, falling back to when it was
last modified if that isn't possible.
See http://stackoverflow.com/a/39501288/1709587 for explanation.
"""
if platform.system() == 'Windows':
return os.path.getctime(path_to_file)
else:
stat = os.stat(path_to_file)
try:
return stat.st_birthtime
except AttributeError:
# We're probably on Linux. No easy way to get creation dates here,
# so we'll settle for when its content was last modified.
return stat.st_mtime
Best Answer
You want to use os.path.expanduser.
This will ensure it works on all platforms:
If you're on Python 3.5+ you can use pathlib.Path.home():