Re: [office-formula] User-Defined Functions

[robert_weir@us.ibm.com]

Eike Rathke <erack@sun.com> wrote on 06/03/2010 10:31:17 AM:
> 
> Hi Eric,
> 
> On Wednesday, 2010-06-02 23:59:14 +0000, Eric Patterson wrote:
> 
> > Have user-defined functions been discussed previously?  Section 5.7
> > defines what to do with Non-Standard function names, but it appears to
> > target functions defined by evaluators, not by users.
> 
> They have been briefly discussed. The outcome was that implementations
> should write them prefixed with "USER.", this seems not to have made it
> into section 5.7


Should there any difference between an implementation-specific extension 
function and a user-specific extension function?  I think there might also 
be 3rd party libraries of extension functions.

In some future release I'd like to see us define some bindings to 
web-based extension functions, maybe something as simple as stating how to 
map function parameters to URL parameters.  So CurrencyConvert(Number 
amt,String src, String dst) as in CurrencyConvert(1.0, "USD","EUR") could 
be defined to map to:

HTTP GET http://www.foo.com?amt=1.0&src=USD&dst=EUR

But for now I don't think we can say anything specific.

Main concern now is name collisions.  Simply saying USER.CurrencyConvert() 
may prevent the name from colliding with future intrinsic functions in 
OpenFormula that might use the name "CurrencyConvert", but it doesn't 
prevent collisions between two users with the same function name.

-Rob