writer-cm 1.0.8

`writer-cm` is a context manager allowing you to atomically write files given a file path.

writer-cm is a context manager allowing you to atomically write files given a file path.

Features

• Cross-platform atomic file writes powered by python-atomicwrites.
• Interface using a file path instead of a file handle, for more compatibility with external libraries (e.g. pandas.to_pickle).
• Automatically create missing directories and set their permissions.
• Automatically set the file permissions.

Installation

pip install writer-cm

Usage

Import and invoke writer_cm as a context manager to obtain a pathlib.Path object to which you can atomically write to:

from writer_cm import writer_cm

with writer_cm("file.txt") as temp:
    # `temp` is a `pathlib.Path` object

    with open(temp, mode="w") as fh:
        fh.write("foo")

# file.txt is atomically written to upon leaving the context manager

with open("file.txt") as fh:
    assert fh.read() == "foo"

writer_cm can also automatically create missing directories and set their permissions (which is done carefully as opposed to relying on Path.mkdir, which itself notes that "[parents] are created with the default permissions without taking mode into account"). Analogously, writer_cm can also set the file permissions too.

from stat import S_IRWXU, S_IRWXG, S_IRUSR, S_IWUSR

with writer_cm("dir1/dir2/dir3/file.txt",
               dir_perms=S_IRWXU | S_IRWXG,  # the default
               file_perms=S_IRUSR, S_IWUSR,  # the default
               ) as temp:
    with open(temp, mode="w") as fh:
        fh.write("foo")

# now `dir1/dir2/dir3`          has been created with u=rwx,g=rwx permissions
#     `dir1/dir2/dir3.file.txt` has been created with u=rw        permissions

For more info on stat, see the official docs.

Finally, pass overwrite=True to overwrite an already existing file; an error is thrown otherwise:

with writer_cm("file.txt", overwrite=True) as temp:
    with open(temp, mode="w") as fh:
        fh.write("bar")

with open("file.txt") as fh:
    assert fh.read() == "bar"