PTOLEMY II - CiteSeerX

MoML
Here, the element named “x” appears both in “top” and in “.top.y”, i.e. the same instance appears in
two different places. Thus, it would have two full names, “.top.x” and “.top.y.x”. However, Ptolemy II
does not support this, as it implements a strict container relationship, where an object can have only
one container. Thus, attempting to parse the above MoML will result in an exception being thrown.
7.3.6 Properties
Entities (and some other elements) can be parameterized. There are two mechanisms. The simplest
one is to use the property element:
The property element has a name, at minimum (the value and class are optional). It is common for the
enclosing class to already contain properties, in which case the property element is used only to set the
value. For example:
In the above, the enclosing object (source, an instance of ptolemy.actor.lib.Ramp) must already
contain a property with the name init. This is typically how library components are parameterized. In
Ptolemy II, the value of a property may be an expression, as in “PI/50”. The expression may refer to
other properties of the containing entity or of its container. Note that the expression language is not
part of MoML, but is rather part of Ptolemy II. In MoML, a property value is simply an uninterpreted
string. It is up to a MoML tool, such as Ptolemy II, to interpret that string.
A property can be declared without a class and without a pre-existing property if it is a pure property,
one with only a name and no value. For example:
A property can also contain a property, as in
A second, much more flexible mechanism is provided for parameterizing entities. The configure
Heterogeneous Concurrent Modeling and Design 201