C＃-创建类似ToString（）的函数

Question

I want to create function, the function name is extend() ,it should after the string,bool,control.like default function ToString()

"123".extend();
false.extend();
textbox1.extend();
extend();

The extend() function can check the input type

if input is string ? ToUpperCase , Substring and Replace the string
if input is bool ? checking the bool 
if input is Control ? check control type , change text,color 
if input is List ? to update global list

And get property name to do something

string SaveString ="";
SaveString.extend();

if(propertyname(object) =="SaveString"){
}

How can i create a function like this ?Thanks

Answer 1

Use Extension Methods

namespace System
{
    public static class ObjectExtension
    {
        public static string Extend(this object input)
        {
            // Do something to input object.
            // For example, you can have different implementation based on its type.

            if (input is string)
            {
            }
            else if (input is bool)
            {
            }
        }
    }
}

There will be no performance penalty while using extension methods on object, because it's compiler feature, see C# Extension Method for Object