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Member not replaced as expected, why?

#2233  Permalink Top

Member not replaced as expected, why?

Apr-16-12 15:53:33

Aims: all the derived classes should inherit some default equations from their base class. When the default equation is not valid for a derived class then it should redeclare it.

Here is a somewhat silly minimalistic example.

Code:

package Pkg



  class Equations

    Real x;

  end Equations;



  class DefaultEquations

    extends Equations;

    equation

      x = 0.0;

  end DefaultEquations;



  class Base

    replaceable DefaultEquations equations extends Equations;

  end Base;



end Pkg;



model DuplicateEquations



    import Pkg.*;



    class CustomizedClass

      extends Base;

      redeclare Equations equations;

      equation

        equations.x = 3;

    end CustomizedClass;



    CustomizedClass customized;



end DuplicateEquations;

For some mysterious reason, the default equation is not overriden:

Code:

omc Test.mo Package.mo

class DuplicateEquations

  Real customized.equations.x;

equation

  customized.equations.x = 0.0;

  customized.equations.x = 3.0;

end DuplicateEquations;

Why is this happening? Why are both x=0 and x=3 generated?

If I comment out the package declaration I get only the expected x=3 equation.

#2234  Permalink Top

Re: Member not replaced as expected, why?

Apr-16-12 16:24:07

Hi,

This is also the behavior of Dymola. You get that extra equation.
You can however do this (redeclare the type, not the component) to get the wanted behavior.

File: Redeclare.mo

Code:


package Pkg



  class Equations

    Real x;

  end Equations;



  class DefaultEquations

    extends Equations;

  equation

      x = 0.0;

  end DefaultEquations;



  class Base

    replaceable class T = DefaultEquations;

    replaceable T equations extends Equations;

  end Base;



model DuplicateEquations



    import Pkg.*;



    class CustomizedClass

      extends Base(redeclare class T = Equations);

    equation

        equations.x = 3;

    end CustomizedClass;



    CustomizedClass customized;



end DuplicateEquations; 



end Pkg;

File: Redeclare.mos

Code:


loadFile("Redeclare.mo"); getErrorString();

instantiateModel(Pkg.DuplicateEquations); getErrorString();

Command line execution:

Code:


adrpo@ida-liu050 ~/dev/OpenModelica/build/bin/bah

$ ../omc.exe Redeclare.mos > trace-Redeclare.mos.txt

File:trace-Redeclare.mos.txt

Code:


true

""

"class Pkg.DuplicateEquations

  Real customized.equations.x;

equation

  customized.equations.x = 3.0;

end Pkg.DuplicateEquations;

"

""

Cheers,
Adrian Pop/

#2235  Permalink Top

Re: Member not replaced as expected, why?

Apr-16-12 17:23:07

Thank you very much, it works!

What is the rationale behind the behavior that caused me the problem? Why is that confusing behavior useful?

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