When connecting to a port, the
modeler must normally explicitly choose which port, for example, by clicking that
area of the symbol in the model. Since the port is not normally a point, but a small
vector graphics shape of its own, it too needs a way to specify where role lines head to
and where they stop. Since the role lines cannot head to the object center??”they would
miss the port??”the port should contain its own target point. Rather than draw one
378 TOOLS FOR DSM
complicated connection boundary that snakes its way around the ports, it is easier to
allow each port to specify its own connection boundary. This also takes care of the
case where a line to one port would also ?¬?rst happen to pass through another port??™s
area: we do not want the line to stop there.
Generated Text Elements Themajority of textelements in amodeling language
will be simple references to property values. Sometimes, more ?¬‚exibility will be
needed, and the text content must be built up from more than one part. For instance,
some labels show text in brackets, like UML??™s ???{abstract}.??? If the text in brackets can
be of different lengths, even this simplest case cannot be handled by a couple of bracket
characters as ?¬?xed text elements either side of the property.
A reasonable subset of such cases can be dealt with by the ability to specify a
sequence of properties and ?¬?xed strings.
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