VB.NET Windows App - Optional Sub Parameter byRef Object default no reference


I have a VB.NET Sub routine with 3 parameters.  The last is " ByRef Optional ilsList As ImageList".

What the routine does internally varies, depending on whether it is called with an ImageList reference.  I therefore need to be able to check if this parameter was called.

I guess I need to assign a DEFAULT value to this reference... not sure how to do this.  I assumed maybe assigning NULL would work and allow me to do an ISREFERENCE() check against the ilsList object.  But this doesn't seem to work.

Any ideas?

Thanks in advance!
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Edy_lConnect With a Mentor Commented:
I assume ilsList  is ImageList type object, so try this

Function A(ByRef Optional ilsList As ImageList = nothing)
     'do your checking here
     If not lsLists is nothing then
          '...some code
     End If
End Function


I think Edy_l is right
quiTechAuthor Commented:
Works great!  Thanks
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