Microsoft 9GD00001 manual Interface Snippet, C# interface snippet template

106Microsoft Visual Studio 2010: A Beginner’s Guide

Figure 4-3 The C# interface snippet template

invokes the Credit method on the runtime Checking or Saving instance. Your code that you wrote for Checking.Credit and Saving.Credit will execute as if your code called them directly as in Listing 4-5. Also observe that we’ve eliminated the duplication because one algorithm, namely IAccount.Credit() in our example, works on both Checking and Saving objects.

Now you can see that interfaces help you treat different types of objects as if they were the same type and helps you simplify the code you need to write when interacting with those objects, eliminating duplication. Imagine what would happen if you were tasked with adding more bank account types to this algorithm without interfaces; you would need to go into the algorithm to write duplicate code for each account type. However, now you can create the new account types and derive them from IAccount; the new account types automatically work in the same algorithm.

The interface Snippet

Before using the interface snippet, open a new file by right-clicking your project in VS Solution Explorer, select Add New Item Code File, and name the file IInvestment.cs (or IInvestment.vb in VB). You’ll have a blank file to work with. To use the interface snippet, type int and press TAB, TAB; you’ll see a snippet template similar to Figure 4-3 (C#) or Figure 4-4 (VB).

Because prefixing interfaces with I is an expected convention, the template highlights the identifier after I.

Figure 4-4 The VB interface snippet template