[Datetime-SIG] Are there any "correct" implementations of tzinfo?

Tim Peters tim.peters at gmail.com
Mon Sep 14 22:22:50 CEST 2015

>> It depends on how expensive .utcoffset()
>> is, which in turn depends on how the tzinfo author implements it.

> No, it does not.  In most time zones, UTC offset in seconds can be computed
> by C code as a 4-byte integer

Which is a specific implementation of .utcoffset().  Which likely has
nothing to do with how most tzinfo authors will implement _their_
.utcoffset().  For example, look at any tzinfo.utcoffset()
implementation that currently exists ;-)

> faster
> than CPython can look up the .utcoffset method. (At least for times
> within a few years around now.) A programmer who makes it slower should
> be fired.

So any programmer who implements .utcoffset() in Python should be
fired?  That's the only way I can read that.

> Yet I agree,  "'premature optimization' applies at this time."

I'm more worried now about premature firing ;-)

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