fdo69552 backward compatibility with optional arguments in calc functions

[Eike Rathke]

Hi Winfried,

On Thursday, 2013-11-28 12:23:56 +0100, Winfried Donkers wrote:

> >The problem I have here is that with CEILING() and FLOOR() the second argument (significance) is optional 
> >and has its default value (1 or -1) depending on the sign of the first argument (value). 
> >How do I obtain this value in formula/source/core/api/token.cxx FormulaMissingContext::AddMoreArgs() 
> >and FormulaMissingContext::AddMissing()?
> 
> >The same problem may apply in sc/source/filter/excel/xeformula.cxx XclExpFmlaCompImpl::AppendTrailingParam()
> 
> I fear I have the answer: I can't make the change to ODF-compliance backwards-compatible.

Indeed, that was the problem with these functions :-(

> When the optional 2nd argument (significance) is not entered by the user it has a value depending on the value of 
> the 1st argument. But this 1st argument can contain a reference, i.e. is not known at the time of writing the file...
> 
> This looks like the WEEKNUM/ISOWEEKNUM problem: to make the formulas comply with ODF1.2, backwards 
> compatibilty is broken... :(
> 
> What is the best way to proceed?

What follows is just a brainstorm, there may be quirks..

Over a long term, spanned over several releases:

0) current release (4.2)

1) for the next release (4.3) implement a second function named a little
   different in the UI (e.g. CEILING_ODF) with the correct handling of
   parameters, do not offer it in the FunctionWizard yet (there's a flag
   in scfuncs.src to suppress functions and their descriptions) and when
   reading from an ODF document a function that does not have the
   optional but so far expected parameter map it to the new function
   (CEILING_ODF), else map it to the old function (CEILING). Both are
   saved as CEILING again in ODF without intervention, not changing
   anything. This enables a release to read and handle future versions
   (or correct ODF files).

2) in the then next release (4.4) activate CEILING_ODF in the
   FunctionWizard, deprecate CEILING saying CEILING_ODF should be used
   and that functions will be renamed in future, but offer both this
   time.

3) in next release (4.5) in the UI rename CEILING to CEILING_OOO and
   rename CEILING_ODF to CEILING. Function descriptions should state
   that.

4) next release (4.6) deactivate CEILING_OOO in the FunctionWizard.
   Users will still see that function name when such a document was
   loaded, but will use CEILING else.

5) next release (4.7) drop CEILING_OOO completely. Users hopefully will
   not miss it ;-)

By the time 4.5 will be published hopefully most users will have
switched from 4.2 to at least 4.3 so will be able to read the new
CEILING of 4.5 as CEILING_ODF

  Eike

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