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Figure 9: Example display from the graph-based interface.
Information associated with the display of a particular query interface is stored as properties of
the class used to model the corresponding paradigm. For example, in the case of the graph-based
interface depicted in gure 9, the class graph interface must reference the base window which contains
the interface, the gures which represent the schema, and the the gures which represent the query.
This is done by dening properties on graph interface which reference the EDEN objects which are
depicted on screen. As the EDEN objects are normal ADAM objects, their object-identiers can be
stored directly in the attributes of graph interface. For example, the following code fragment shows
part of the denitions of query mixin and graph interface:
class query_mixin {
attributes {
internal_form: set of query_component;
...
}
...
}
class graph_interface is_a query_mixin {
attributes {
picture_window: picture;
...
}
...
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