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Optional reflection topic Optional reflection topic – 'mix-in' classes A `mix-in' class is one that provides a small amount of functionality. Mix-ins are intended to simplify implementation; a mix-in class rarely models a real-world entity. Here is an example. It may be useful to allow objects to be able to save their states to a disk file. For example, when I start my word processor, its appearance is very much as it was when I last used it (position on screen, layout of buttons, etc). Clearly the objects that model the screen appearance are able to `remember' their variables from the last use of the program. The programmer may get this feature by defining a class called, say, CanSaveToDisk, and making all other classes subclasses of CanSaveToDisk. This is an example of a mix-in class; it provides a small, well-defined piece of program functionality. Java does not readily support mix-in programming. Why? Can anything be done about this? Reflect back to the 'dimond of death' and problems of multiple inheritance — the use of `mix-in' programming presents a particular problem in this regard. Why?
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