preferring [] or () in list of error codes?

Mel mwilson at the-wire.com
Sat Jun 13 17:25:27 CEST 2009


Gunter Henriksen wrote:
[ ... ]
> I guess to me, fundamentally, the interpretation of
> tuple as a sequence whose elements have semantic meaning
> implicitly defined by position is a relatively abstract
> intrepretation whose value is dubious relative to the
> value of immutability, since it seems like a shortcut
> which sacrifices explicitness for the sake of brevity.

The immutability makes it easier to talk about the semantic meanings.  After 
you do
>     event_timestamp = (2009, 06, 04, 05, 02, 03)
there's nothing that can happen to the tuple to invalidate
>     (year, month, day, hour, minute, second) = event_timestamp
even though, as you say, there's nothing in the tuple to inform anybody 
about the year, month, day, ... interpretation.

And of course there's nothing in a C struct object that isn't in the 
equivalent Python tuple.  The difference is that the C compiler has arranged 
all the outside code that uses the struct object to use it in the correct 
way.  The only object I've found in Python that truly replaces a struct 
object in C is a dict with string keys -- or an object that uses such a dict 
as its __dict__.


	Mel.




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