PTOLEMY II - CiteSeerX

MoML
This class extends Gen by adding two properties, and then sets the properties of the component entities
to have values that are expressions.
7.3.11 Inheritance
MoML supports inheritance by permitting you to extend existing classes. For example, consider
the following MoML file:
Here, the “derived” class extends the “base” class by adding another entity to it, and “instance” is an
instance of derived. The class “derived” can also give a source attribute, which gives a URL for the
source definition.
A derived class (or subclass) can contain additional entities, relations, ports, and links. However, it
cannot remove entities, relations, ports or links defined in the base class. Moreover, it cannot add links
that are exclusively between ports and relations defined in the base class. New links must involve
either a port or a relation that is new in the derived class.
7.3.12 Directors
Recall that a clustered graph in MoML has no semantics. However, a particular model has semantics.
It may be a dataflow graph, a state machine, a process network, or something else. To give it
semantics, Ptolemy II requires the specification of a director associated with a model, an entity, or a
class. The director is a property of the model. The following example gives discrete-event semantics to
a Ptolemy II model:
...
This example also sets a property of the director. The name of the director is not important, except that
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