OpenOffice.org BASIC Guide.pdf - OpenOffice.org wiki

Procedures and Functions 35
The method for passing parameters to procedures and functions in OpenOffice.org Basic is virtually
identical to that in VBA. By default, the parameters are passed by reference. To pass parameters as
values, use the ByVal keyword. In VBA, you can also use the keyword ByRef to force a parameter to be
passed by reference. OpenOffice.org Basic recognizes but ignores this keyword, because this is already
the default procedure in OpenOffice.org Basic.
Optional Parameters
Functions and procedures can only be called up if all the necessary parameters are passed
during the call.
OpenOffice.org Basic lets you define parameters as optional, that is, if the corresponding
values are not included in a call, OpenOffice.org Basic passes an empty parameter. In the
following example the A parameter is obligatory, whereas the B parameter is optional.
Sub Test(A As Integer, Optional B As Integer)
' ...
End Sub
The IsMissing function checks whether a parameter has been passed or is left out.
Sub Test(A As Integer, Optional B As Integer)
Dim B_Local As Integer
' Check whether B parameter is actually present
If Not IsMissing (B) Then
B_Local = B ' B parameter present
Else
B_Local = 0 ' B parameter missing -> default value 0
End If
' ... Start the actual function
End Sub
The example first tests whether the B parameter has been passed and, if necessary, passes
the same parameter to the internal B_Local variable. If the corresponding parameter is not
present, then a default value (in this instance, the value 0) is passed to B_Local rather than
the passed parameter.
The ParamArray keyword present in VBA is not supported in OpenOffice.org Basic.