[Python-Dev] iso8601 parsing

[Steven D'Aprano]

On Wed, Oct 25, 2017 at 04:32:39PM -0400, Alexander Belopolsky wrote:
> On Wed, Oct 25, 2017 at 3:48 PM, Alex Walters <tritium-list at sdamon.com> wrote:
> >  Why make parsing ISO time special?
> 
> It's not the ISO format per se that is special, but parsing of str(x).
> For all numeric types, int, float, complex and even
> fractions.Fraction, we have a roundtrip invariant T(str(x)) == x.
> Datetime types are a special kind of numbers, but they don't follow
> this established pattern.  This is annoying when you deal with time
> series where it is common to have text files with a mix of dates,
> timestamps and numbers.  You can write generic code to deal with ints
> and floats, but have to special-case anything time related.

Maybe I'm just being slow today, but I don't see how you can write 
"generic code" to convert text to int/float/complex/Fraction, but not 
times. The only difference is that instead of calling the type directly, 
you call the appropriate classmethod.

What am I missing?



-- 
Steven