[Python-Dev] basenumber redux (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Wed Jan 18 21:36:20 CET 2006

Jason Orendorff wrote:

Really this is just further proof that type-checking is a royal pain in Python. Or rather, it's not hard to cover the builtin and stdlib types, but it's hard to support "duck typing" too. Are we going about this the right way?

It's not as bad. There is nothing wrong with restricting the set of acceptable types if callers would have no problems to convert their input into one of the acceptable types.

In the imaplib example, requesting that a broken-down time is passed as a tuple or a time.struct_time is not too hard for a caller. It will be formatted as

dt = time.strftime("%d-%b-%Y %H:%M:%S", tt)

so it needs to have the right number of fields. Callers having other kinds of sequence can easily use tuple(L) to convert their data into what the function accepts.

Regards, Martin

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