nameof Operator in C# 6.0

C# 6.0 Features Series

• How to try C# 6.0 and Rosyln?
• Getter-only (Read Only) Auto Properties in C# 6.0
• Lambda and Getter Only Auto-Properties in C# 6.0
• Initializers for Read-Only Auto Properties in C# 6.0
• Initializers via Expression Auto Properties in C# 6.0
• C# 6.0 – A field initializer cannot reference the non-static field, method, or property
• Lambda Expression for Function Members in C# 6.0
• Dictionary Initializers (Index Initializers) in C# 6.0
• Expression Bodies on Methods returning void in C# 6.0
• using keyword for static class in C# 6.0
• Unused namespaces in Different Color in Visual Studio 2015
• Null-Conditional Operator in C# 6.0
• Null-Conditional Operator and Delegates
• nameof Operator in C# 6.0
• Contextual Keywords in C#
• String Interpolation in C# 6.0
• Exception Filters in C# 6.0
• Await in Catch and finally block in C# 6.0

C# 6.0 introduces the new nameof operator that returns the name of the program element.

For example , assume that you want to throw the ArgumentNullException for a parameter , you would do something like the code snippet shown in the earlier version of C#.

public void PerformAction(Point point1, Point pointy)
{
    if(point1 == null)
    {
        throw new ArgumentNullException("point1");
    }
}

In the above code snippet , the ArgumentNullException takes the parameter of type string with the name of the parameter point1 . Now , if you refactor this method by renaming the parameter point1 to pointx , the parameter of ArgumentNullException still remains as “point1” . This might lead to inconsistency.

The nameof operator solves this problem . You could rewrite the above code snippet as shown below.

public void PerformAction(Point point1, Point pointy)
{
    if(point1 == null)
    {
        throw new ArgumentNullException(nameof(point1));
    }
}

Now , when you rename the first parameter “point1” , the corresponding name used with the nameof operator would also be updated.