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[Python-Dev] iso8601 parsing

Nick Coghlan ncoghlan at gmail.com
Thu Oct 26 01:37:48 EDT 2017 
On 26 October 2017 at 07:30, Chris Barker <chris.barker at noaa.gov> wrote:

> +1 on a classmethod constructor
> +0 on a based-on-type default constructor
>
> +inf on SOMETHING!
>
> Let's get passed the bike shedding and make this work!
>

I'll also note that these aren't either/or outcomes: adding a str-specific
classmethod *doesn't* preclude implicitly calling that class method from
the default constructor later based on the input type.

For example, decimal.Decimal.from_float() was added before the type
constructor gained native support for float inputs, due to concerns about
potential binary-vs-decimal rounding errors arising from doing such
conversions implicitly.

So we can add "datetime.fromisoformat(isotime: str)" now, and then *if* we
later decide to support the "type(x)(str(x)) == x" numeric invariant for
the datetime classes, that can be specified as "If the constructor
arguments consist of a single string, that is handled by calling the
fromisoformat class method".

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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