[Libreoffice] [REVIEW][3-4] date change regression fdo#44385

[Noel Power]

On 21/01/12 01:42, Andrew Douglas Pitonyak wrote:
> I believe that you intend to cause the following behavior:
>
> date + num        Date
> date - num         Date
> date * num         Double
> date / num          Double
> date + date        Date [2]
> date - date         Double [3]
> date * date         Double
>
> [2] - I prefer this, but I would not spend much energy advocating it.
> [3] - I would have subtraction return the same type as addition. So, 
> if "date + date" returns "date", then I would return date for [3]. If 
> you have [2] return a double, then have [3] return a double.
>
> My opinion is that you now just pick one and do it. I will call it a 
> consensus and back your decision in the unlikely event I am ever 
> called upon to do so.
>
so, in general terms I can accept that subtraction will result in either 
a Date or a Double ( depending on whether one or both sides of the 
operation are Dates ). I can also accept that adding a number to a Date 
should result in a Date also makes sense. I have more difficulty 
understanding why adding 2 dates should give a Date as a result and am 
(like you) a little uncomfortable about the lack of symmetry regarding 
treatment of '-/+'. However, having an overriding rule that ensures any 
'+' operation involving a Date type results in a Date type does ensure 
that those operations you mentioned previously e.g. something like
     Date1 + num + Date2
will result in a Date type maybe explains the reason for this lack of 
symmetry in the treatment of '+/-'. Anyway since I can't make anymore 
sense of this I prefer to defer to both the previous behaviour ( and 
additionally behavriour of mso vba ) and modify the behaviour in the 
minimum way, e.g. just change the behaviour of Date - 'num' to return a 
Date. So, I will commit a change to provide the behaviour as is 
described in the table above ( including the asymmetric treatment of +/- 
). That's not to say we couldn't or shouldn't change the behaviour of 
'+' later, just right now I am not comfortable with doing that.

Noel