exception handling

Question 1

How do we classify errors based on their origin

Answer 1

New and bubbled-up

Question 2

What are further distinction can you have for new and bubbled-up errors

Answer 2

Recoverable and non-recoverable

Question 3

What are the 4 scenarios

Answer 3

• New recoverable
• Bubbled-up recoverable
• New non-recoverable
• Bubbled-up non-recoverable

Question 4

Example of New Recoverable error

Answer 4

LBYL

def add_song_to_db(song)
    if song.year is None
        song.year = 'Unknown'

Question 5

Example of Bubbled-up recoverable error

Answer 5

def add_song_to_db(song):
    try:
        artist = get_artist_from_db(song.artist)
    except NotFound:
        add_artist_to_db(song.artist)

Question 6

Example of new non-recoverable

Answer 6

def add_song_to_db(song):
    if song.name is None:
        raise ValueError('Song must have a name')

Question 7

Example of bubbled-up non-recoverable error

Answer 7

def get_new_song():
    song = get_song_from_user()
    add_song_to_db(song)

Question 8

Why is it ok to let errors bubble-up?

Answer 8

Separation of concerns. Let higher layers with more context decide how to handle errors. You may not even want to print as it’s not the layers job to concern itself with how output should be handled.