bug#11115: linux date arithmetic

[Ruediger Meier]

On Wednesday 28 March 2012, Eric Blake wrote:
> On 03/28/2012 03:23 PM, Bruno Haible wrote:
> > Eric Blake wrote:
> >> the parser is faced with an ambiguity between:
> >>
> >> (11:38 +1) minute
> >> 11:38 (+1 minute)
> >
> > What is the first interpretation meant to mean?
>
> The time 11:38 in the timezone UTC+1, plus the unit represented by
> 'minute'.
>
> > "10:38 minute" or "12:38 minute" is not a time designation I have
> > ever heard in spoken nor written English.
>
> True, 'minute' in isolation, without a 'plus one' qualifier, is
> unusual; but we have to continue to parse it in isolation since
> scripts may now be relying on it.
>
> > If you ditch this interpretation, there is no ambiguity.
>
> Yes, we're in violent agreement here: the added context of a +1 (and
> in particular, of a '+ 1' with a space after the +), should indeed
> favor the spoken preference of a time with no timezone, followed by a
> completed relative designation; rather than of a relative designation
> with only an implied quantity.  It's just that getdate.y is a hairy
> mess to properly implement that change without breaking other
> worthwhile constructs, so I won't be the one volunteering.

BTW there is an interesting dateutils project not yet finished but worth 
to have look
https://github.com/hroptatyr/dateutils

cu,
Rudi