Evaluting structural parameters and array modifications

[Mahder Alemseged Gebremedhin]

If you are not already aware of this, there seems to be a problem when constant evaluation is involved for array modifications

model ConservationEquation
  parameter Boolean aa = true;
end ConservationEquation;

model PartialMixingVolume
  parameter Boolean bp = true;
  ConservationEquation ba(aa = bp);
  Real p;  
end PartialMixingVolume;

model Pipe
  PartialMixingVolume[2] ca(bp = {false, false});
end Pipe;

Gets correctly flattened to

class Pipe
  parameter Boolean ca[1].bp = false;
  parameter Boolean ca[1].ba.aa = ca[1].bp;
  Real ca[1].p;
  parameter Boolean ca[2].bp = false;
  parameter Boolean ca[2].ba.aa = ca[2].bp;
  Real ca[2].p;
end Pipe;

---

However if you add an if equation, which I believe causes a constant evaluation as follows

model ConservationEquation
  parameter Boolean aa = true;
end ConservationEquation;

model PartialMixingVolume
  parameter Boolean bp = true;
  ConservationEquation ba(aa = bp);
  Real p;
initial equation
  if ba.aa then
    p = 3;
  end if;  
end PartialMixingVolume;

model Pipe
  PartialMixingVolume[2] ca(bp = {false, false});
end Pipe;

The model flattens to

class Pipe
  parameter Boolean ca[1].bp = false;
  final parameter Boolean ca[1].ba.aa = false;
  Real ca[1].p;
  parameter Boolean ca[2].bp = false;
  final parameter Boolean ca[2].ba.aa = {false, false};
  Real ca[2].p;
initial equation
  if {false, false} then
    ca[1].p = 3.0;
  end if;
  if {false, false} then
    ca[2].p = 3.0;
  end if;
end Pipe;

The binding for ca[2].ba.aa is now cevaled to an array. Same for the loop condition.

It does not happen for the first element of the array. It only happens for the rest of the elements always (2nd, 3rd, ...).

[Mahder Alemseged Gebremedhin]

BTW this is the reason of failure for a number of tests in the library coverage (e.g. Building models). e.g.

​https://libraries.openmodelica.org/branches/newInst/BuildSysPro/files/BuildSysPro_BuildSysPro.IBPSA.Fluid.MixingVolumes.BaseClasses.Validation.MixingVolumeHeatMoisturePort.err

​https://libraries.openmodelica.org/branches/newInst/Buildings_latest/files/Buildings_latest_Buildings.Experimental.DistrictHeatingCooling.Validation.IdealSmallSystem.err

The surprising thing is that these models can pass the FrontEnd and BackEnd as if nothing is wrong and then fail on compilation of generated code.

[Per Östlund]

I know, we've got many tickets open about this issue in various forms, and it's what I've been trying to fix for several months now. It should hopefully be fixed any day now.

[Mahder Alemseged Gebremedhin]

Oh Okay. I though so too. Then do your thing. Hopefully this helps.

[Per Östlund]

Fixed in 4cf73067.

[Francesco Casella]

Backported to 1.14.0 and 1.15.0