Step 3: Inheriting from OLE classes

ObjectWindows includes classes that let windows, documents, and views interact with the ObjectComponents classes.

The ObjectWindows OLE classes include default implementations for most normal OLE operations. To adapt an existing ObjectWindows program to OLE, change its derived classes so they inherit from the OLE classes. The following table shows which OLE class replaces each of the non-OLE classes.

Non-OLE class	OLE class
owl::TFrameWindow	TOleFrame
owl::TMDIFrame	TOleMDIFrame
owl::TDecoratedFrame	TOleFrame
owl::TDecoratedMDIFrame	TOleMDIFrame
owl::TWindow	TOleWindow
owl::TDocument	TOleDocument
owl::TView	TOleView
owl::TFileDocument	TOleDocument
owl::TDialog	TOleDialog

The TOleFrame and TOleMDIFrame classes both derive from decorated window classes. The OLE 2 user interface requires containers to handle tool bars and status bars. Even if the container has no decorations, servers might need to display their own in the container's window. The OLE window classes handle those negotiations for you.

Wherever your existing OWL program uses a non-OLE class, replace it with an OLE class, as shown here.

Before

// pre-OLE declaration of a window class
class TMyFrame: public owl::TFrameWindow
{ /* declarations */ );

After

// new declaration of the same window class
class TMyFrame: public TOleFrame   { /* declarations */ );

Note

If the implementation of your class makes direct calls to its base class, be sure to change the base class calls, as well. Response tables also refer to the base class and need to be updated.