Ian East wrote: > PS Just for the record, I seriously doubt the value of inheritance. > Outside of big application frameworks, I have seen precious little > worthwhile use. Somewhere (don't press me for reference) I have seen > published surveys that support the claim of little tangible benefit. At > very least, IMHO it should be confined to compile-time, and not invade > run-time. It's (synchronous) message-passing that matters. Inheritance is still the subject of debate for its merits in code re-use. C++ has, however, clouded the issue by its highly impure implementation. Certainly within Siemens, code re-use by means of inheritance has been found seriously wanting. One way in which inheritance seems to be clearly beneficial is when an abstract class is given concrete implementations to meet particular requirements. This is typical of much of the Java standard APIs. Perhaps it's fair to say, inheritance seems to be more useful the fewer layers of inheritance are applied. Rick -- Richard Beton B.Sc. C.Phys. M.Inst.P. Roke Manor Research Limited (http://www.roke.co.uk/) --------- Standard Disclaimer about my own views etc etc -------- --------- My mail client accepts rich text (HTML) mail -------- Welsh Highland Railway: http://www.whr.co.uk/WHR/WHR.html