[Libreoffice] [REVIEW][3-4] date change regression fdo#44385
Andrew Douglas Pitonyak
andrew at pitonyak.org
Thu Jan 19 18:10:36 PST 2012
On 01/19/2012 09:03 PM, Andrew Douglas Pitonyak wrote:
> On 01/16/2012 08:01 AM, Eike Rathke wrote:
>> Hi Noel,
>> On Friday, 2012-01-13 09:51:33 +0000, Noel Power wrote:
>>> this change ( the variant ) is what is on master, here the
>>> intention is as Andrew pointed out ( in a previous mail discussing
>>> the regression ) to allow operations on date types return dates (
>>> regardless of the operation ) which seems reasonable.
>> Not every operation on date types should return a date, i.e.
>> substracting two dates should return a number of days (I don't think
>> adding/multiplying/dividing two dates makes sense, but it should return
>> a number of days as well).
> The original code verified that a date was used in at least one
> argument, and, if so, then a date is returned. Eike, to follow your
> suggestion of NOT returning a date if we expect that the answer should
> be a number of days, then we would want to check both parameters, and
> if both are of type date then return a double rather than date. If you
> really desire to strive for accuracy, then what you want to say is
> that if two dates are involved and there is a subtraction, then you
> desire the elapsed time between the two date objects.
> I need to be careful in what I say because I am not intimate with the
> code, but, I believe that a date is internally represented as a
> double. I also seem to remember that a "time" is a date that has "zero
> days". This leaves a day that cannot be represented (well, it won't
> print as a date anyway, at least I think it did not when I last tested
> it long before LibO existed).
> One may choose to argue that date arithmetic makes no sense (ie, what
> does it mean to add today to today, or to multiply today by 2), but I
> believe that the original solution was written to allow for the common
> case and do the expected thing. So, Perhaps I have code such as
> (time_1 + time_2 - time_3), the intent seems to be to determine the
> difference between time_2 and time_3 and add that to time_1. In the
> original code, that would work. I suppose that if we add a check to
> verify that one parameter is a date and that the other is not, then
> our result would be mostly as expected, but that feels onerous. It is
> a bit difficult and fraught with peril, however, because I believe
> that if the new time passes midnight (ie, 24 hours), then it will
> suddenly display as a date rather than a time.
Oh my.... Looks like Date and Time are represented as different types
My Macro Document: http://www.pitonyak.org/AndrewMacro.odt
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