Understanding Interface-Based Programming - Interfaces in Visual Studio 2005
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Visual Studio 2005 has excellent support for implementing and refactoring interfaces. As a component developer, your classes will occasionally need to implement an interface defined by another party. Instead of copying and pasting the interface definition, or typing it in, you can use Visual Studio 2005 to generate a skeletal implementation of the interface. A skeletal implementation is a do-nothing implementation: all implanted methods or properties throw an exception of type Exception and do not contain any other code. A skeletal implementation is required to at least get the code compiled as a starting point for your implementation of an interface, and it prevents clients from consuming a half-baked implementation. To have Visual Studio 2005 generate a skeletal interface implementation, you first add the interface to the class derivation chain. When you finish typing the interface name (such as IMyInterface), Visual Studio 2005 marks a little underscore tag under the I of the interface name. If you hover over IMyInterface, Visual Studio 2005 pops up a smart tag with a tool tip, “Options to implement interface.” If you click the down arrow of the smart tip you can select from two options in the menu, implementing the interface either implicitly or explicitly (see Figure 3-2).
Figure 3-2. Using Visual Studio 2005 to provide a skeletal interface implementation
Once you select an option, Visual Studio 2005 creates a skeletal implementation of the interface on your class and scopes it with a collapsible#regiondirective. For example, consider this interface definition:
public interface IMyInterface
{
void Method1();
int Method2(int number);
string Method3();
}
If you select explicit implementation, Visual Studio 2005 generates this skeletal implementation:
public class MyClass : IMyInterface
{
#region IMyInterface Members
void IMyInterface.Method1()
{
throw new Exception();
}
int IMyInterface.Method2(int number)
{
throw new Exception();
}
string IMyInterface.Method3()
{
throw new Exception();
}
#endregion
}
Implementing a skeletal interface also works with generic interfaces.
Visual Basic 2005 has only IntelliSense-level skeletal interface implementation, and it doesn’t generate a region around the skeleton.
Next: Interface Refactoring >>
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 This article is excerpted from chapter three of Programming .NET Components, Second Edition, written by Juval Lowy (O'Reilly, 2006; ISBN: 0596007620). Check it out today at your favorite bookstore. Buy this book now.
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