We have successfully created the IsPalindrome() extension method in the previous section. It's quite easy to call the extension method since it's defined inside the same namespace as the caller method. In other words, the IsPalindrome() extension method and the Main() method are in the same namespace. We don't need to add a reference to any module since the method is there along with the caller. However, in common practice, we can create extension methods in the other assemblies, which we usually call class library. The use of the library will ease the use of the extension method since it can be reused, so we can use the extension method in many projects.
We are going to create an extension method in the Class Library and call it in another project. Let's create a new Class Library project named ReferencingNamespaceLib.csproj and insert the following code into the ExtensionMethodsClass.cs file:
using System; namespaceReferencingNamespaceLib...