help asked for Calc jump function with empty arguments

[Winfried Donkers]

Hi Eike,

>> With IFERROR and IFNA these situation should return an empty value to be compatible with Excel.
>AFAIK also Excel does not allow a null argument for IFERROR() second parameter, but I'm not sure, I'd have to check.


Excel replaces an empty argument with an empty value, that is to say, the function description says 
'If value or value_if_error is an empty cell, IFERROR treats it as an empty string value ("").'
and =IFERROR(1/0;) returns an empty cell, not an error message.

>> With IF, the behaviour is described in ODFF1.2.
> Note that there seems to be a typo in the spec, IfFalse is mentioned twice to be considered to be 0, the first (two consecutive ;; case) probably should be IfTrue.

ODFF1.2 syntax is ' IF( Logical Condition [ ; [ Any IfTrue ] [ ; [ Any IfFalse ] ] ] )' and in semantics the handling of null arguments is described, but -IF(1;;) return an error in Calc.

>> My question is, where should this behaviour best be put in the code?

> I think the right place would be ScInterpreter::Interpret() at the end where the final result is obtained. There's a check
>     if( pCur->GetOpCode() == ocPush )
> and if not an error is set. An ocMissing here could be propagated through to the ScFormulaResult, then
>     bool isValue( formula::StackVar sv )
> in sc/source/core/tool/formularesult.cxx would need to handle formula::svMissing as well, the ScFormulaResult::GetDouble() already returns 0.0 in such case.

I will try. The problem so far with SCInterpreter::Interpret was that I need to know what the function was, as IFERROR and IF have different responses to null arguments (in the case of IF I also need to know the values of the first argument as that is to be the result).

>> And as these functions are jump functions, how best to access/modify the stack or FormulaToken?
> Don't ;-)
I won't ;-)

Winfried