The concrete syntax is severely limited: symbols may consist of only a single
geometrical ?¬?gure, and the only supported ?¬?gures are rounded rectangles or their
extremeversions, rectangles and ellipses. Bitmap or other external images can be used,
but do not scale, and compartment shapes are used to handle aggregations. In a novel
decision, the elements representing graphical symbols are drawn in a ???sidebar??? to the
main metamodel, paralleling the elements they represent. Confusingly, the natural
representation of these elements is not used in the metamodel: whether it is a red
rectangle or a blue ellipse, the element is always shown as a gray rounded rectangle.
CURRENT TOOLS 393
DSL Tools are at level 3 in our scale of tool evolution: the metamodel is
transformed by generators into C# and possibly C++ code. This code is extended with
handwritten code for constraints, proper symbols, and improved editor behavior. The
result is then compiled, built and opened as the DSM tool in a separate debugging
instance of Visual Studio. When the metamodel is changed, regenerated and
recompiled, this instance must be closed and a new instance opened.
Currently, there is little support for updating a modeling language. If the name of a
modeling language concept is changed, the corresponding model elements all
disappear, effectively being deleted when the model is opened.
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