Python – Handles the 79-character limit when writing python type annotations

While writing the script, I ended up with the function signature shown below

def do_multiprocess_action(some_argument: str, communication_pipe: typing. Optional[multiprocessing.connection.Connection]) -> subprocess. Popen:

To comply with PEP8, I split the definition as follows

def do_multiprocess_action(some_argument: str,
                           communication_pipe: typing. Optional[multiprocessing.connection.Connection]
                           ) -> subprocess. Popen:

But for type annotations, this line is too long. What is the usual way to deal with this problem?

You can define the annotation first, and then write your function:

MultiprocessingConnection = typing. Optional[
    multiprocessing.connection.Connection]

def do_multiprocess_action(some_argument: str, 
    communication_pipe: MultiprocessingConnection) -> subprocess. Popen: