ODL File Example

The following example shows the .odl file for the Lines sample file, extracted from Lines.odl.

   uuid(3C591B20-1F13-101B-B826-00DD01103DE1),      // LIBID_Lines.
   helpstring("Lines 1.0 Type Library"),
library Lines
   #define DISPID_NEWENUM -4

      uuid(3C591B25-1F13-101B-B826-00DD01103DE1),  // IID_Ipoint.
      helpstring("Point object."),
   interface IPoint : IDispatch
      [propget, helpstring("Returns and sets x coordinate.")]
      HRESULT x([out, retval] int* retval); 
      [propput, helpstring("Returns and sets x coordinate.")]
      HRESULT x([in] int Value);

      [propget, helpstring("Returns and sets y coordinate.")]
      HRESULT y([out, retval] int* retval); 
      [propput, helpstring("Returns and sets y coordinate.")]
      HRESULT y([in] int Value);

// Additional interfaces omitted for brevity.

      uuid(3C591B27-1F13-101B-B826-00DD01103DE1),      // IID_Ipoints.
      helpstring("Points collection."),
   interface IPoints : IDispatch
      [propget, helpstring("Returns number of points in collection.")]
      HRESULT Count([out, retval] long* retval);

      [propget, id(0),
      helpstring("Given an index, returns a point in the collection.")]
      HRESULT Item([in] long Index, [out, retval] IPoint** retval);

      [propget, restricted, id(DISPID_NEWENUM)]   // Must be propget.
      HRESULT _NewEnum([out, retval] IUnknown** retval);

// Additional interface omitted for brevity.

      uuid(3C591B22-1F13-101B-B826-00DD01103DE1),   // IID_Iapplication
      helpstring("Application object."),
   interface IApplication : IDispatch
      [propget, helpstring("Returns the application of the object.")]
      HRESULT Application(   [out, retval] IApplication** retval);

      helpstring("Returns the full name of the application.")]
      HRESULT FullName([out, retval] BSTR* retval);
      [propget, id(0),
      helpstring("Returns the name of the application.")]
      HRESULT Name([out, retval] BSTR* retval);

      [propget, helpstring("Returns the parent of the object.")]
      HRESULT Parent([out, retval] IApplication** retval);

      HRESULT Visible([in] boolean VisibleFlag);
      [propget, helpstring
      ("Sets or returns whether the main window is visible.")]
      HRESULT Visible(   [out, retval] boolean* retval);

      [helpstring("Exits the application.")]
      HRESULT Quit();

// Additional methods omitted for brevity.

      [helpstring("Creates new Point object initialized to (0,0).")]
      HRESULT CreatePoint(   [out, retval] IPoint** retval);

      uuid(3C591B21-1F13-101B-B826-00DD01103DE1),   // CLSID_Lines.
      helpstring("Lines Class"),
   coclass Lines
      [default] interface IApplication;
         interface IDispatch;

The example describes a library named Lines that imports the standard OLE library Stdole.tlb. The #define directive defines the constant DISPID_NEWENUM, which is needed for the _NewEnum property of the IPoints collection.

The example shows declarations for three interfaces in the library: IPoint, IPoints, and IApplication. Because all three are dual interfaces, their members can be invoked through IDispatch or directly through virtual function tables (VTBLs). In addition, all of their members return HRESULT values and pass their return values as retval parameters. Therefore, they can support the IErrorInfo interface, through which they can return detailed error information in whatever way they are invoked.

The IPoint interface has two properties, X and Y, and two pairs of accessor functions to get and set the properties.

The IPoint interface is a collection of points. It supports three read-only properties, each of which has a single accessor function. The Count and Item properties return the number of points and the value of a single point, respectively. The _NewEnum property, required for collection objects, returns an enumerator object for the collection. This property has the restricted attribute, indicating that it should not be invoked from a macro language.

The IApplication interface describes the application object. It supports the properties Application, FullName, Name, Parent, Visible, and Pane. It supports the methods Quit, CreateLine, and CreatePoint.

Finally, the script defines a coclass named Lines. The appobject attribute makes the members of the coclass (IApplication and IDispatch) globally accessible in the type library. IApplication is defined as the default member, indicating that it is the programmability interface intended for use by macro languages.