safer 0.9.5

Try to import all modules below a given root

Safely write or print to a file, leaving it unchanged if there’s an exception

Writes happen on a temporary file, which is only copied over the original file when the context completes successfully.

This means that safer will temporarily use as much disk space as the old file and the new file put together.

Example:

import safer

with safer.open(filename, 'w') as fp:
    for line in source():
       fp.write('this and that')

    if CHANGED_MY_MIND:
        # filename will be unchanged
        raise ValueError

# or

with safer.printer(filename) as print:
    print('this', 'and', 'that')
    print('two', 'lines', sep='\n', end='\n---\n')

    if CHANGED_MY_MIND:
        # filename will be unchanged
        raise ValueError