IDL Forward Declaration

20.3.10 IDL Forward Declaration

RTI Code Generator supports forward declarations of structs, value types, and unions, meaning that you can use a type before defining it.

A type that is not defined yet can only appear as the element type of a sequence definition, as an @external member, or (if the type being defined is not a union) as an @optional member.

In the following example, MyStructFD is not defined before it is used as a member on MyStruct:

struct MyStructFD;

struct MyStruct {

    sequence <MyStructFD> member_1;

    @external MyStructFD member_2;

    @optional MyStructFD member_3;

};

union MyUnion switch (long) {

    case 1: sequence <MyStructFD> member_1;

    case 2: @external MyStructFD member_2;

    // Incomplete type cannot be used with @optional when defining a union

    // default: @optional MyStructFD member_3;

};

struct MyStructFD {

    long member_FD;

};

Forward declarations are not supported in the Python language.