[masklinn]

Don't forget the part where checking for preconditions opens you up to race conditions e.g.

    if not file_exists(filepath):
        stderr("invalid config filepath!")
    # filepath is removed by an external tool
    config = read_file(filepath) # blows up file does not exist

[bbradley406]

Is there still a chance of a race condition when you use the "with" operator? It seems like this is one of the major use cases it was designed for

[kqr]

It depends on how you use it! If you use it to acquire the resource, as in

    with open(fn, 'r'):
        ...

then generally the answer is no, since that is the same thing as the equivalent `try…finally`. If someone removes the file after it's being opened it will not be completely wiped until it's closed.