safer 0.9.8

Try to import all modules below a given root

✏️safer: safe file writer ✏️

Safely write or print to a file, so that the original file is only overwritten if the operation completes successfuly.

Works on Python versions 2.7 through 3.8 and likely beyond.

Writes are performed on a temporary file, which is only copied over the original file after the context completes successfully. Note that this temporarily uses as much disk space as the old file and the new file put together.

EXAMPLES

safer.writer

# dangerous
with open(config_filename, 'w') as fp:
    json.dump(cfg, fp)  # If this fails, the config file gets broken

# safer
with safer.writer(config_filename) as fp:
    json.dump(cfg, fp)  # If this fails, the config file is untouched

safer.printer

with safer.printer(configs_filename) as print:
    for cfg in configs:
        print(json.dumps(cfg))

API call documentation

safer.writer(file, mode='w', create_parents=False, delete_failures=True, suffix='.tmp', **kwargs)

A context that yields a writable stream, like from open(), but undoes any changes to the file if there’s an exception.

Arguments:

file:

Path to the file to be opened

mode:

Mode string passed to open()

create_parents:

If True, all parent directories are automatically created

delete_failures:

Are partial files deleted if the context terminates with an exception?

suffix:

File suffix to use for temporary files

kwargs:

Keywords passed to built-in open

safer.printer(file, mode='w', create_parents=False, delete_failures=True, suffix='.tmp', **kwargs)

A context that yields a function that prints to the opened file, but undoes any changes to the file if there’s an exception.

Arguments:

file:

Path to the file to be opened

mode:

Mode string passed to open()

create_parents:

If True, all parent directories are automatically created

delete_failures:

Are partial files deleted if the context terminates with an exception?

suffix:

File suffix to use for temporary files

kwargs:

Keywords passed to built-in open