How to update the visibility of an object based on a parameter

Connections have at least two important variables. The flow variable and not-flow variable (and then stream stuff but lets not talk about those). For clarity I will reference the Fluid connector and its variables m_flow (flow variable) and p (not flow variable).

When your building components it is important to specify if that component is setting the value for the m_flow or p. For example, you do not want to connect two pressure loss components (sets m_flow) together.

The fluid connectors in MSL are defined as port_a (design inlet) and port_b (design outlet). To specify if a port sets m_flow or not, DynamicPipe opts to use the PartialTwoPort component that has an object (black ellipse) in the icon layer that toggles its visibility based on a parameter (port_a_exposesState) which can be modified when PartialTwoPort is extended (i.e., PartialTwoPortFlow).

However, this feature does not work. The parameter will not change its display when the parameter is changed (i.e., the black ellipse on DynamicPipe never goes away).

Below is a simple example demonstrating the concept. When the model "RunMe" is simulated the parameter showBall = false because number <> 1. However, the ball is still visible.

Partial Model setting the object that should appear/disappear:

partial model ballIcon

// input Boolean showBall; // Tried this as well to no avail.

protected 
  parameter Boolean showBall = true;

  annotation (Icon(coordinateSystem(preserveAspectRatio=false), graphics={
          Ellipse(
          extent={{-40,40},{40,-40}},
          lineColor={0,0,0},
          fillPattern=FillPattern.HorizontalCylinder,
          fillColor={255,255,0},
          visible=showBall)}),
          Diagram(coordinateSystem(
          preserveAspectRatio=false)));
end ballIcon;

Extending model:

model extendsBallIcon

  extends ballIcon(showBall=(number==1));

  parameter Real number = 1;

end extendsBallIcon;

Model that should show a ball that appears or disappears based on "number":

model RunMe

  extendsBallIcon Ball(number=3)
    annotation (Placement(transformation(extent={{-10,-10},{10,10}})));

end RunMe;

Is there something that can be corrected to this approach so the GUI of a component when used (i.e., on the diagram layer) will work? Or do connectors GUI need to capture the flow/not-flow element that is defined by a component to assist in model usage (i.e., change port_a from description design inlet to defined flow variable).

Using Dymola 2017 (tested with the same results on Dymola 2016 as well)

Update:

Knowing the simple case works using DynamicSelect leads me to a real application. The following change appears to cause the icon to not toggle its visiblity.

In extendsBallIcon replacing:

  extends ballIcon(showBall=(number==1));

  parameter Real number = 1;

with

  // Boolean Example
   extends ballIcon(showBall=(number==true));

   final parameter Boolean number = (modelStructure==Modelica.Fluid.Types.ModelStructure.av_b);
   parameter Modelica.Fluid.Types.ModelStructure modelStructure = Modelica.Fluid.Types.ModelStructure.av_b;

Solution

Modelica language specification states in section 18.6.6: "Any value (coordinates, color, text, etc) in graphical annotations can be dependent on class variables using the DynamicSelect expression." That is, visible=DynamicSelect(true, showBall) in your example will display the ellipse only if showBall is true.