Forward Declaration of IDL Interfaces

• In an IDL definition, you must declare an IDL interface before you reference it.
• A forward declaration declares the name of an interface without defining it.
• This feature of IDL allows you to define interfaces that mutually reference each other.

  For example, IDL interface Account could include an attribute of IDL interface type Bank, to indicate that Account stores a reference to a Bank object.

  If the definition of interface Bank follows the definition of interface Account, you would forward declare Bank as follows:

  
      module Finance { 
        // Forward declaration of Bank. 
        interface Bank; 
        interface Account { 
          readonly attribute Bank branch; 
          ... 
        }; 
        // Full definition of Bank. 
        interface Bank { 
          ... 
        }; 
      }; 
  

• The syntax for a forward declaration is the keyword interface followed by the interface identifier.