Improve inheritance of classes in MultiBody

[tobolar]

The inheritance of classes is not done consequently. See for example #3737 or https://github.com/modelica/ModelicaStandardLibrary/issues/2171#issuecomment-280661422

[beutlich]

The inheritance of classes is not done consequently. See for example #3737 or #2171 (comment)

Or also https://github.com/modelica/ModelicaStandardLibrary/pull/3725#issuecomment-762969249

[tobolar]

Or also https://github.com/modelica/ModelicaStandardLibrary/pull/3725#issuecomment-762969249

I would proceed with Constraints once #3725 is merged.

[tobolar]

I have started to apply the inheritance properly but see currently two problems.

1. I really stumble on the usage of cardinality in the MultiBody classes. It is generally used in base classes such as Interfaces.PartialOneFrame_b but not in the classes which could inherit it, e.g. Parts.Fixed. Moreover, the cardinality is deprecated and even if #1410 gets some solution, it is obviously yet not resolved. So we can

   1. Wait untill #1410 is solved or
   2. Implement a "half" solution for classes only where cardinality is used already.

2. The connector's description in the particular classes is moslty more specific compared to a base class. E.g. frame_b in Parts.Fixed is sayed to be "Coordinate system fixed in the world frame", but it is "Coordinate system fixed to the component with one cut-force and cut-torque" in Interfaces.PartialOneFrame_b. Any possibility to retain the more precise text?

[beutlich]

It should (?) be egal Modelica to overwrite the description in the extends statement, see for example

model M "Extend from PartialTwoFrames, but set other frame descriptions"
  extends Modelica.Mechanics.MultiBody.Interfaces.PartialTwoFrames(
    frame_a "This is frame A ...",
    frame_b "... and this is frame B");
end M;

[christiankral]

This is somehow related with #2455

[tobolar]

It should (?) be egal Modelica to overwrite the description in the extends statement...

@beutlich Thanks, I will use this.

[TManikantan]

@tobolar Hi!!! ,I recently assumed the responsibility of project deputy. Did you happen to fix the issue? would you please commit the fix,. We can get it reviewed and merge it.

[tobolar]

I started this a long time ago but let it be due to lack of time. Will try to recall.