Refactoring code using Extract Method in Visual Studio 2010

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Refactoring is the process of improving your code after it has been written, by changing the internal structure of the code without affecting its functionality. Extract Method is a refactoring operation in Visual Studio 2010 that provides an easy way to create a new method from a code fragment, in an existing member.

In order to use Extract Method, you require to select a code fragment. Let us see an example:

Check this piece of code

In the code above, the process of checking the validity of the connection string should ideally be put in a new method. This is very simple using the Extract method refactoring. Just select the code fragment and right click > Refactor > Extract Method (or Ctrl + R, Ctrl + M) as shown below:

In the Extract Method dialog box, enter the new method name and hit OK

When you click OK, Visual Studio 2010 creates a new method and moves the selected
code fragment to the body of the new method, in our case AlternateConnectionString(). It also creates appropriate parameters and even returns a value, if needed, by the calling code.

The original code (where the code fragment was), is replaced with a call to the new method, with any applicable parameters that are to be passed to the new method or add a local variable to receive the return value.

The code fragment after refactoring looks like this:

Note: The Extract Method Refactor is smart! For eg: if your code does not access any instance-specific data, the Extract method refactoring makes the new method static.

Similarly, you can even extract a single line of code or a portion of a code, as its own method.

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About The Author

Suprotim Agarwal, Developer Technologies MVP (Microsoft Most Valuable Professional) is the founder and contributor for DevCurry, DotNetCurry and SQLServerCurry. He is the Chief Editor of a Developer Magazine called DNC Magazine. He has also authored two Books - 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook.

Follow him on twitter @suprotimagarwal.