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stringtextgraphicsmodelica

Modelica macro to display String

Modelica knows few macros to display values of variables or names of components on the diagram, documented in the language specification: https://specification.modelica.org/v3.4/Ch18.html#text

The below model displays the value of a Real variable and String variable as expected, but it fails to display the String from the replaceable package. Is that not possible?

model StringVisual
  replaceable package Medium = Modelica.Media.R134a.R134a_ph;
  parameter String medname=Medium.mediumName;
  parameter String teststringA = "Hello World";
  parameter String teststringB = teststringA;
  parameter Real myreal=3.14;

equation 
  when initial() then
    Modelica.Utilities.Streams.print(medname);
  end when;

  annotation (Diagram(graphics={
        Text(
          extent={{0,-50},{100,-100}},
          textColor={30,100,200},
          textString="%{myreal}"),
        Text(
          extent={{-100,60},{-10,0}},
          textColor={30,100,200},
          textString="%{medname}"),
        Text(
          extent={{-100,100},{-20,40}},
          textColor={30,100,200},
          textString="%{Medium.mediumName}"),
        Text(
          extent={{0,100},{100,40}},
          textColor={30,100,200},
          textString="%{teststringA}"),
        Text(
          extent={{0,50},{100,0}},
          textColor={30,100,200},
          textString="{%teststringB}")}));
end StringVisual;
Solution

  • TL;DR: Currently not.

    The simplest interpretation of "value" is to show the parameter-setting, and for parameter String medname=Medium.mediumName; that means that the "value" is Medium.mediumName.

    In Dymola (since 2017) that is extended to show the value by evaluating the parameter-settings when possible. However, that cannot currently handle package-variables (directly or indirectly) and external functions are deliberately excluded.

    Clarified: Thus neither medname norMedium.mediumName will work since they are both package-variables.

    Note that: Using "%p" only works for non-hierarchical names, the safer alternative is "%{p}".

    Thus the last one should be rewritten as "%{Medium.mediumName}" - and even that is not fully according to the specification as it isn't a component-reference.