This keyword in C#, Linq?

What's the meaning of this usage of the this keyword开发者_运维百科 in C#:

public static ExcelRow Hide(this ExcelRow row)
  {
   return row.Hide(true);
  }

Is this Linq ? If yes, what's the difference between ExcelRow row and this ExcelRow row ?

Note: It's not a spelling bug, there's no point or other accessor in between.

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In this particular context it denotes that the Hide method is an Extension Method that can be called on instances of the ExcelRow type.

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It means that it is an extension method. This refers to the instance of ExcelRow for which the method is invoked.

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The method you have above is an extension method (msdn.microsoft.com/en-us/library/bb383977.aspx). The "this ExcelRow row" part of the signature means that the method extends an excelRow object. So you can use it on an instance of ExcelRow. Eg: ExcelRow row = new ExcelRow(); row.Hide(); The ExcelRow part of the definition (after the static keyword) simply means that your extension method returns an instance of the ExcelRow Type