[LEAPSECS] comp.risks post in need of response

Ashley Yakeley ashley at semantic.org
Tue Dec 9 23:02:45 EST 2008

On Tue, 2008-12-09 at 17:22 -0500, John Cowan wrote:

> The library does not at all do what you think it does.

Thank you, yes, this is all largely correct.

> Corresponding to

> UniversalTime as a moment of time, there is DiffTime as a duration of

> time, represented with a precision of 1 ps.

Just to clarify, DiffTime represents relative clock time, i.e. the
difference between two AbsoluteTimes, and not the difference between two

> The second is intended to represent UTC, and is implemented using a

> integral MJD date and a DiffTime representing between 0 and 86401 seconds

> inclusive, with a fixed precision of 1 ps.

It's supposed to be exclusive of 86401s. But actually the library
doesn't stop you entering any DiffTime at all, and calculations
involving NominalDiffTime will clip any time beyond 86400s.

You can see the other modules in the library here:

I was considering creating a "tz" or "zoneinfo" library, that would be
able to provide the available leap-second table, but I haven't got
around to it.

Ashley Yakeley

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