Programming C#

Exporting .NET Components

You can export your .NET class for use with existing COM components, although this is an unusual requirement. The Regasm tool will register the metadata from your component in the system registry.

You invoke Regasm with the name of the DLL. For example:

Regasm myAssembly.dll

This will export your component’s metadata to the Registry. For example, you can create a new C# DLL project in which you re-create your four-function calculator, as shown in Example 22-8.

Example 22-8. The four-function calculator in a DLL

using System;

namespace Programming_CSharp
{
    public class Calculator
    {
        public Calculator(  )
        {
            
        }
        public Double Add (Double left, Double right)
        {
            return left + right;
        }
        public Double Subtract (Double left, Double right)
        {
            return left - right;
        }
        public Double Multiply (Double left, Double right)
        {
            return left * right;
        }
        public Double Divide (Double left, Double right)
        {
            return left / right;
        }
    }
}

You save this to a file named Calculator.cs in a project named ProgrammingCSharpDLL. After building this project, you can register it with:

Regasm ProgrammingCSharpDLL.dll

A quick check of the Registry shows that a PROGID was created for the DLL, as shown in Figure 22-18.

Figure 22-18. The Registry after registering the DLL

You can now invoke the four-function calculator as a COM object using standard VBScript. For example, you can create a tiny Windows Script ...