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

[Ethan Furman]

On 08/04/2014 06:39 PM, Steven D'Aprano wrote:
> 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.

What are the downsides of:

dt = datetime.datetime.now()	# assuming this works ;)
sdt = str(dt)
ndt = datetime.datetime(std)
print(dt == ndt)
#True

--
~Ethan~