David Moner wrote: > I was exaclty thinking about this while seeing this proposal for the > ITEM_STRUCTURE change to a VALUE_CLUSTER: > > http://www.openehr.org/wiki/display/spec/openEHR+2.x+RM+proposals+-+lower+information+model#openEHR2.xRMproposals-lowerinformationmodel-CandidateA.1AddVALUECLUSTER%2CRemoveITEMSTRUCTUREtypes > > > It is an example of multiple inheritance not supported by Java and some other > languages.
Multiple inheritance is easily implemented in Java and C# ... via interfaces. The problem is that you often need to duplicate code. For example, in that diagram, VALUE_CLUSTER inherits from both ELEMENT and CLUSTER. In C# you can't do that, so you would probably declare ValueCluster as implementing two interfaces, IElement and ICluster; then you would copy the implementations of Element and Cluster into ValueCluster. Java would do something similar, although the naming convention of the interfaces might be different. (In C#, you might even decide to avoid some of the code duplication by using extension methods. Or maybe not ... it might cause more trouble than it solves.) Peter
