Having the button pressing policy speci?¬?ed in a role allows reusing existing button
de?¬?nitions and specifying its usage information separately only when relevant: The
same button element could then be used multiple times in models and have different
usage situations.
Language De?¬?nition Guidelines Typically, the best way to start language
de?¬?nition is to extend the selected MOC with basic domain concepts: ?¬?rst, add the
most essential and most used language elements. Then, continue by identifying their
connections along with the various rules and constraints. As most of us will be
de?¬?ning our ?¬?rst language for the domain, it is important to test the modeling concepts
IDENTIFYING AND DEFINING MODELING CONCEPTS 245
early. This means trying out the language early on. Having a working language, albeit
limited in expressive power, and gradually testing and extending it makes language
de?¬?nition agile.
You don??™t need to de?¬?ne all the rules in the beginning as the modeling concepts
could change. The same applies for notation and generators. Implementing them too
early, when the language is not yet stable, can waste time and effort. Some guidelines
for language de?¬?nition are as follows:
. Follow established naming conventions: While de?¬?ning the concepts, it is
usually best to use exactly the same names and naming policies for the language
concepts as are already used.
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