MATLAB COM Builder

Processing varargin and varargout Arguments

When varargin and/or varargout are present in the original MATLAB function, these parameters are added to the argument list of the class method as the last input/output parameters. You can pass multiple arguments as a varargin array by creating a Variant array, assigning each element of the array to the respective input argument.

The following example creates a varargin array to call a method resulting from a MATLAB function of the form y = foo(varargin).

• Function foo(x1 As Variant, x2 As Variant, x3 As Varaint, _
               x4 As Variant, x5 As Variant) As Variant
     Dim aClass As Object
     Dim v(1 To 5) As Variant
     Dim y As Variant 
     
     On Error Goto Handle_Error
     v(1) = x1
     v(2) = x2
     v(3) = x3
     v(4) = x4
     v(5) = x5
     aClass = CreateObject("mycomponent.myclass.1_0")
     Call aClass.foo(1,y,v)
     foo = y
     Exit Function
  Handle_Error:
     foo = Err.Description
  End Function
  

The MWUtil class included in the MWComUtil utility library provides the MWPack helper function to create varargin parameters. See Utility Library for more details.

The next example processes a varargout parameter into three separate arguments. This function makes use of the MWUnpack function in the utility library. The MATLAB function used is varargout = foo(x1,x2).

• Sub foo(Xout1 As Variant, Xout2 As Variant, Xout3 As Variant, _
          Xin1 As Variant, Xin2 As Variant)
     Dim aClass As Object
     Dim aUtil As Object
     Dim v As Variant
      
     On Error Goto Handle_Error
     aUtil = CreateObject("MWComUtil.MWUtil")
     aClass = CreateObject("mycomponent.myclass.1_0")
     Call aClass.foo(3,v,Xin1,Xin2)
     Call aUtil.MWUnpack(v,0,True,Xout1,Xout2,Xout3)
     Exit Sub
  Handle_Error:
     MsgBox(Err.Description)
  End Sub
  

Calling the Methods of a Class Instance

Handling Errors During a Method Call