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fs.base
=======
This module contains the basic FS interface and a number of other essential interfaces.
fs.base.FS
----------
All Filesystem objects inherit from this class.
.. autoclass:: fs.base.FS
:members:
fs.base.SubFS
-------------
A SubFS is an FS implementation that represents a directory on another Filesystem. When you use the :meth:`fs.base.FS.opendir` method it will return a SubFS instance. You should not need to instantiate a SubFS directly.
For example::
from fs.osfs import OSFS
home_fs = OSFS('foo')
bar_fs = home_fs.opendir('bar')
fs.base.NullFile
----------------
A NullFile is a file-like object with no functionality. It is used in situations where a file-like object is required but the caller doesn't have any data to read or write.
The :meth:`fs.base.FS.safeopen` method returns an NullFile instance, which can reduce error-handling code.
For example, the following code may be written to append some text to a log file::
logfile = None
try:
logfile = myfs.open('log.txt', 'a')
logfile.writeline('operation successful!')
finally:
if logfile is not None:
logfile.close()
This could be re-written using the `safeopen` method::
myfs.safeopen('log.txt', 'a').writeline('operation successful!')
If the file doesn't exist then the call to writeline will be a null-operation (i.e. not do anything).
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