Python's filesystem abstraction layer
Python's Filesystem abstraction layer.
Think of PyFilesystem's
FS objects as the next logical step to
file objects. In the same way that file objects abstract a
single file, FS objects abstract an entire filesystem.
Let's look at a simple piece of code as an example. The following
function uses the PyFilesystem API to count the number of non-blank
lines of Python code in a directory. It works recursively, so it will
.py files in all sub-directories.
def count_python_loc(fs): """Count non-blank lines of Python code.""" count = 0 for path in fs.walk.files(filter=['*.py']): with fs.open(path) as python_file: count += sum(1 for line in python_file if line.strip()) return count
We can call
count_python_loc as follows:
from fs import open_fs projects_fs = open_fs('~/projects') print(count_python_loc(projects_fs))
project_fs = open_fs('~/projects') opens an FS object that
maps to the
projects directory in your home folder. That object is
count_python_loc when counting lines of code.
To count the lines of Python code in a zip file, we can make the following change:
projects_fs = open_fs('zip://projects.zip')
Or to count the Python lines on an FTP server:
projects_fs = open_fs('ftp://ftp.example.org/projects')
No changes to
count_python_loc are necessary, because PyFileystem
provides a simple consistent interface to anything that resembles a
collection of files and directories. Essentially, it allows you to write
code that is independent of where and how the files are physically
Contrast that with a version that purely uses the standard library:
def count_py_loc(path): count = 0 for root, dirs, files in os.walk(path): for name in files: if name.endswith('.py'): with open(os.path.join(root, name), 'rt') as python_file: count += sum(1 for line in python_file if line.strip()) return count
This version is similar to the PyFilesystem code above, but would only
work with the OS filesystem. Any other filesystem would require an
entirely different API, and you would likely have to re-implement the
directory walking functionality of
PyFilesystem2 owes a massive debt of gratitude to the following developers who contributed code and ideas to the original version.
- Ryan Kelly
- Andrew Scheller
- Ben Timby
Apologies if I missed anyone, feel free to prompt me if your name is missing here.
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