How to instantiate a COM object using interop in Delphi Prism

What is the correct syntax for instantiating a COM object in Delphi Prism using COM interop - new does not seem to do the job.

I've added it as a reference to the website project. Here is the relevant code:

开发者_如何学Cmethod _Default.Button1_Click(sender: System.Object; e: System.EventArgs);
var
   FModel: MarketBuilderLib.MarketBuilderModel;
begin
  FModel := New MarketBuilderLib.MarketBuilderModel;
end;

Fails to compile with the message:

Error 1 
(PE190) "MarketBuilderLib.MarketBuilderModel" is an interface and cannot be 
instantiated

I understand the message but not sure how to do it. Many thanks for any help.

You can attempt to instantiate your COM object by using the CreateInstance method in the System.Activator class. The equivalent code might look like this:

var
  FModel: MarketBuilderLib.MarketBuilderModel;
begin
  FModel := (MarketBuilderLib.MarketBuilderModel)Activator.CreateInstance(GetTypeFromProgID("{PROG ID}"));
end;

Note that you will need to get the type from GetTypeFromProgID using the Program Identifier otherwise you will generate an InvalidComObjectException.