[Python-3000] PEP 3113 (Removal of Tuple Parameter Unpacking) (original) (raw)

Raymond Hettinger python at rcn.com
Sun Mar 4 22:22:14 CET 2007

[Ka-Ping Yee]

In summary, all of the arguments for removing this feature are of the form "It won't hurt very much if we remove the feature"; the arguments for keeping the feature are of the form "This feature is useful and good for the language." Notice the asymmetry: there are no arguments that removing it will actually yield a better language, only arguments that the harm caused by removing it will be small.

Well said. I agree whole-heartedly; however, Brett did present another argument beyond "it won't hurt much". I think his root motivation was that the feature was difficult to implement for some reason or another.

FWIW, I would like the feature to be kept. I've found it useful in that it documents the function signature more completely when dealing with arguments that are already pre-packed into tuples (such as records returned from SQL queries or CSV row readers):

def contact_info_update(timestamp, sequence_number, (name, address, phone,

email), backup=True): . . .

contact_info_update(now(), seqnum, cursor.fetchone(), backup=False)

I think it is important to make explicit that the function depends on a specific layout for the contact record tuple and have that dependency show-up in tooltips when I write the function call.

Another example comes from a spherical navigation module with several tuple representations for movement (lat_offset, long_offset) versus (dist, direction).

Raymond

More information about the Python-3000 mailing list