Item809: CALC TIMEADD month is wrong

Priority:	CurrentState:	AppliesTo:	Component:	WaitingFor:
Enhancement	Confirmed	Engine	SpreadSheetPlugin

from the code:

       $value *= 3600*24*30.42 if( $scale =~ /^mon/i );  # FIXME: exact calc
       $value *= 3600*24*365   if( $scale =~ /^year/i ); # FIXME: exact calc

-- SvenDowideit - 20 Jan 2009

Hmm. I understand and partly agree.

If I add one month to a date I expect same day of month, same time and simply the calendar month increased to the next one.

But the way the CALC works I can actually also specify 0.6 month. I can have a formular that calculates decimal numbers and add a fraction of a month.

So the exact way to implement this change needs to be carefully thought of.

Also to implement this we really need a non-default CPAN lib. We should consider including one in our own Foswiki CPAN lib. Like Date::Calc.

That also enables adding additional features like adding working days.

Changing to enhancement.

-- KennethLavrsen - 07 Feb 2009

I was thinking about DateTimePlugin, but that plugin also does not handle inc_month. Shortcoming of that plugin (and date handling in general in Perl) is that dates before 1970 are not supported. Date::Calc may be a solution, but DateTime.pm seems more featurefull.

-- ArthurClemens - 07 Feb 2009