Alternative for Optional arguments or method overload?
Hi,
I saw in one of the comments on this blog: http://blogs.msdn.com/cumgranosalis/archive/2006/04/11/WebServiceAsyncUdfs.aspx#1282044 that UDFs do not support overloading of methods.
I also read in this article: http://msdn2.microsoft.com/en-us/library/ms495224.aspx that a UDF method cannot have Optional arguments.
I am trying to create UDF methods with same name, but with different number of parameters for Excel Services. Something like:
[UdfMethod(IsVolatile = true)]
[ComVisible(false)]
public object MyUDFMethod(object[,] arg1)
{
......
}
[UdfMethod(IsVolatile = true)]
[ComVisible(false)]
public object MyUDFMethod(object[,] arg1, object[,] arg2)
{
......
}
OR
[UdfMethod(IsVolatile = true)]
[ComVisible(false)]
public object MyUDFMethod(object[,] arg1, [Optional]object[,] arg2)
{
......
}
Is there any alternative to have this supported by Excel Services?
Thanks.
Aleksandra
Answers
You could use "param arrays" - a trailing set of alternating # of arguments, that your UDF gets as an array.
[UdfMethod(IsVolatile = true)]
public object MyUDFMethod(params object[] arg)
{
......
}
Each element in a param array can also be an array in itself, so if you need each one to be an object[,], you could define the param array as "params object[][,]".
The only thing I am not sure of is how this works as a COM interface.
Danny
All Replies
You could use "param arrays" - a trailing set of alternating # of arguments, that your UDF gets as an array.
[UdfMethod(IsVolatile = true)]
public object MyUDFMethod(params object[] arg)
{
......
}
Each element in a param array can also be an array in itself, so if you need each one to be an object[,], you could define the param array as "params object[][,]".
The only thing I am not sure of is how this works as a COM interface.
Danny
Actually, first suggestion is not working for some reason:
public object MyUDFMethod(params object[] arg)
But, the second one solves the problem:
public object MyUDFMethod(params object[][,] arg)
Thanks a lot.
Aleksandra
