User`s guide

3 Programming with Excel Builder Components
3-6
Creating an Instance of a Class
Before calling a class method (compiled MATLAB function), you must create an
instance of the class that contains the method. VBA provides two techniques
for doing this:
•
CreateObject function
• Visual Basic
New operator
CreateObject Function
This method uses the Visual Basic application program interface (API)
CreateObject function to create an instance of the class. To use this method,
dimension a variable of type
Object to hold a reference to the class instance
and call
CreateObject with the class’ programmatic identifier (ProgID) as an
argument as shown in the next example.
Function foo(x1 As Variant, x2 As Variant) As Variant
Dim aClass As Object
On Error Goto Handle_Error
aClass = CreateObject("mycomponent.myclass.1_0")
' (call some methods on aClass)
Exit Function
Handle_Error:
foo = Err.Description
End Function
Visual Basic New Operator
This method uses the Visual Basic New operator on a variable explicitly
dimensioned as the class to be created. Before using this method, you must
reference the type library containing the class in the current VBA project. Do
this by selecting the
Tools menu from the Visual Basic editor, and then
selecting
References… to display the Available References list. From this list
select the necessary type library.
The following example illustrates using the
New operator to create a class
instance. It assumes that you have selected
mycomponent 1.0 Type Library
from the
Available References list before calling this function.
Function foo(x1 As Variant, x2 As Variant) As Variant