Extension objects to a class -

well discovered extension methods, extension methods allow extending methods , functionality existing type without needing change code : here

// extending using extension methods static class myextensionmethods {     public static int negate(this int value)     {         return -value;     } }  static void main(string[] args) {     //using extension method     int i2 = 53;     console.writeline(i.negate()); } 

my question :

is possible same thing object, example add int id form, can :

form frm = new form();  frm.id = 2; 

yes, can create extension methods on type of class want.

however, example not method property , cannot create extension properties.

the following valid:

static class formextensions{      public static void setid(this form form, int someid)     {         // someid here     } }  // call this: form frm = new form(); frm.setid(2);