Axel Simon
One question which I asked earlier is: a) Shall the classes containt the widget's functionality as well? (Or, alternatively: b) Shall we have a class for each attribute (like "onActivate") and create instances for all widgets that implement it.)
Having the type system detect use of unsupported attributes is highly desirable but having a separate class for each attribute is unappealing since I expect there's a lot of them. Just one of the disadvantages is that type signatures get very, very long so you're disinclined to write them and error messages get quite outrageously long (I once got a two-page long error message from Hugs when using T-Rex). Is there some way to cluster the member functions so that each class provides multiple attributes and to use inheritance to further reduce the size of contexts one typically writes? In particular, can we exploit the inheritance hierarchy in the widget sets we are building on? -- Alastair