Modelica coding standards / new OpenModelica compiler frontend - modelica

Question

looks like a issue with new OpenModelica compiler frontend. I am using official release version of openmodelica 1.14 on windows-7 64bit OS.
package Test1_14
model M1
parameter Integer size = 2 "matrix size";
parameter Real A[size] = {1.0, 1.0};
Real B[size];
Real T = 1;
Real P = 2;
equation
B = A * (T/P);
end M1;
model M1_Extn
Real C[size];
Real D[size];
equation
for J in 1:size loop
C[J] = Func1(T);
D[J] = C[J] / P;
end for;
end M1_Extn;
function Func1
input Real a;
output Real b;
algorithm
b := a*a;
end Func1;
model M1_Combined
parameter Integer size = 2 "matrix size";
Real B[size];
Real T = 1;
Real P = 2;
extends M1_Extn;
equation
B = D;
end M1_Combined;
end Test1_14;
When I compile the model ‘M1_Combined’, the code generation fails with new OpenModelica compiler frontend. Export FMU also fails with the same error.
Is my code as per Modelica programing standards?
How do I declare variables - size, T, P in the model M1_Extn and still use keyword ‘extends’ in ‘M1_Combined’ ?

Answer 1

This is because the old frontend did not handle the "extends" correctly, according to the Modelica Specification. The new frontend does it correctly.
To be clear, you cannot define a variable in this class and then use it in the extends any other way than via a modification (and via inner/outer, via redeclare as element). An example is below, you cannot use a inside M1.
package TestExtends
model M1
parameter Real b = a;
end M1;
model M2
parameter Real a = 1;
extends M1;
end M2;
end TestExtends;
To fix your model so that is according to Modelica standards, you can do:
package Test1_14
model M1
parameter Integer size = 2 "matrix size";
parameter Real A[size] = {1.0, 1.0};
Real B[size];
Real T = 1;
Real P = 2;
equation
B = A * (T/P);
end M1;
model M1_Extn
parameter Integer size = 2;
Real T = 1;
Real P = 2;
Real C[size];
Real D[size];
equation
for J in 1:size loop
C[J] = Func1(T);
D[J] = C[J] / P;
end for;
end M1_Extn;
function Func1
input Real a;
output Real b;
algorithm
b := a*a;
end Func1;
model M1_Combined
extends M1_Extn(size=2, T = 1, P = 2);
Real B[size]; // this one works as you can use things defined in extends.
equation
B = D;
end M1_Combined;
end Test1_14;