[Python-ideas] strptime without second argument as an inverse to __str__

Steven D'Aprano steve at pearwood.info
Tue Aug 5 03:39:44 CEST 2014


On Mon, Aug 04, 2014 at 10:56:56PM +0200, Wolfgang Maier wrote:
[...]
> it does hold true in 3.x, but the documented behavior is slightly more 
> complex (I assume also in 2.x):
> 
> datetime.__str__()
>     For a datetime instance d, str(d) is equivalent to d.isoformat(' ').

Since str(d) is documented to use a well-defined format, then I agree 
that it makes sense to make the second argument to d.strptime optional, 
and default to that same format. The concern I had was the sort of 
scenario Skip suggested: I might write out a datetime object as a string 
on one machine, where the format is X, and read it back elsewhere, where 
the format is Y, leading to at best an exception and at worse incorrect 
data.

+1 on the suggestion.


-- 
Steven


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