Modelica：检查可替换 package 或 model 的相等性

Question

In my Modelica system model, I have a replaceable package (medium, fluid properties) and a replaceable model (pressure loss model). Can I somehow check whether a certain model or package is selected? The following approach does not work, but maybe explains what I want to achieve:

replaceable package Medium = Modelica.Media.Water.WaterIF97_ph;
Boolean isWater = (Medium == Modelica.Media.Water.WaterIF97_ph);

I was thinking of something similar like in python, were you can use type(variable) or isinstance(object, class) . This approach seems to be doable in many languages, but is it possible in Modelica?

One workaround I thought of was to add some (or use an existing) constant inside the replaceable model/package and use that in the comparison, eg constant String mediumName or constant Integer correlationID , but I would see that as a workaround.

The workaround seems to work when using Integers, but not when using Strings. Any comment?

With comparison of constant Integer, I can calculate the correct value for the Boolean, but I hit another problem (in Dymola at least): When I use the Boolean in the annotation Dialog enable, it does not work. Is there a rule when the value of the Boolean gets evaluated?

Answer 1

The medium packages already have a property mediumName that you can compare, for instance using the code:

Boolean isWater = Modelica.Utilities.Strings.isEqual("WaterIF97", Medium.mediumName);

Best regards, Rene Just Nielsen