package TestChoices



model M1

  parameter Real T ;

  Real f;

equation

  f = 1. + time;

end M1;



model M2

  parameter Real T ;

  Real f;

equation

  f = 2. + time;

end M2;



model fullmodel

  parameter Integer I = 1;

  parameter Real x = 5. ;

  Real y ;

  M1 m1;

  M2 m2;

//

equation



if 1 == I then

  y = m1.f;

elseif  1 == 2  then

 y = m2.f;

end if;



end fullmodel;



  model Essai

   fullmodel full2(I = 2, x = 2.5)  annotation(

      Placement(visible = true, transformation(origin = {-20, 20}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));

  equation



  end Essai;





end TestChoices;

Not sure what you need, if it is an if equation or a when equation.
You can also use conditional components but that is a bit more
involved as you need connectors and connects to handle the
various choices:
https://specification.modelica.org/main … eclaration
https://mbe.modelica.university/compone … nt_models/

Thank you,

I have just combined your different propositions to change the instantiation of M1 and M2 like this :

  M1 m1 if I==1 "Conditional component";
  M2 m2 if I==2 "Conditional component";

works and avoids to run both models as can be seen in the flat modelica :

class TestChoices2.fullmodel
  final parameter Integer I = 1;
  parameter Real x = 5.0;
  Real y;
  parameter Real m1.T;
  Real m1.f;
equation
  m1.f = 1.0 + time;
  y = m1.f;
end TestChoices2.fullmodel;

without conditional definition :

class TestChoices2.Essai
...
equation
  full2.m1.f = 1.0 + time;
  full2.m2.f = 2.0 + time;
  full2.y = full2.m1.f;
end TestChoices2.Essai;

I migth choose this solution with the parameter "I" in a inner/outer declaration (like system in the fluid library) so that all the models and connectors can be change with only an parameter.

Maybe it's an old fortran 66's way of programmation !