Need to sniff for 404 error codes

[Stuart Bishop]

A common pattern with python-swiftclient is:

try:
    conn.head_object(container, obj)
except ClientException as err:
    if err.http_status != 404:
        raise
    [ ... handle not found ... ]

This is ugly and annoying from a developer's perspective. If a specific exception, inheriting from both swiftclient.exceptions.ClientException and the standard Python LookupError, was returned specifiably for HTTP 404 it would become possible to actually write Pythonic code whilst being fully compatible with existing code like the above:

try:
    conn.head_object(container, obj)
except LookupError:
    [ ... handle not found ... ]

[Nick Moffitt (nick-moffitt)]

The requests library (which is currently the gold standard for handling HTTP in Python) manages to provide both interfaces (exceptions or member variable inspection) successfully:

http://docs.python-requests.org/en/latest/user/quickstart/#response-status-codes