Why we use “this” in Extension Methods?

Question

I want to ask why we use \"this\" keyword before the parameter in an extension method (C# Language)........... like this function :

    public static int ToI         


        

Answer 1

For info, the significance of this as a contextual-keyword here is largely that it avoids introducing a new keyword. Whenever you introduce a new keyword you risk breaking code that would have used it as a variable / type name. this has a few useful features:

• it is close enough to indicating that this relates to an instance method
• it is an existing keyword...
• ...that would have been illegal when used in that location

This means that no existing code will be broken.

Beyond the choice of this as the keyword, it is just a convenient syntax for the compiler, and more convenient than adding [Extension] manually. Without either, it would just be a static method, without any special behaviour.