Remove `OperationVariable` class about basyx-python-sdk

[zrgt]

Unfortunately if we want to keep OperationVariable class we will have to revert some changes made in d0cf3d5

To solve #146 we may introduce a new property submodel_element_id_short in OperationVariable and do smth like this in Operation.__init__:

self.input_variable = base.NamespaceSet(self, [("submodel_element_id_short", True)], input_variable)

[TorbenD]

Good points. How about the integration into the server-implementation which will come next? Maybe it would be easier to still remain with the OperationVariable for less adaption in other applications based on the sdks in future.

[zrgt]

@jkhsjdhjs Can you take care of the issue?

[zrgt]

We may have to reconsider the decision to eliminate the OperationVariable class due to possible problems with DotAAS version updates. If new attributes are added to OperationVariable in the future, we will be forced to build the class again and integrate those attributes. Such changes in the future will also require changes to our users' code and impact the backwards compatibility.

@jkhsjdhjs , @s-heppner , @TorbenD what do you think?

[jkhsjdhjs]

Such changes in the future will also require changes to our users' code and impact the backwards compatibility.

Good point. On the other hand adding attributes to OperationVariable would require a new version, and seeing how breaking changes are introduced even in release candidates, I doubt there won't be any in the next minor version. Thus you could also argue, that we might as well remove OperationVariable, because one breaking change more or less will probably not make a big difference.

[zrgt]

Such changes in the future will also require changes to our users' code and impact the backwards compatibility.

Good point. On the other hand adding attributes to OperationVariable would require a new version, and seeing how breaking changes are introduced even in release candidates, I doubt there won't be any in the next minor version. Thus you could also argue, that we might as well remove OperationVariable, because one breaking change more or less will probably not make a big difference.

The removing of OperationVariable class would still affect the backwards compatibility.

[jkhsjdhjs]

Sure, my argument is that there are breaking changing with every new version of the metamodel, attributes are renamed all the time or are of a different type in a new version. So if we can't expect much backwards compatibility for other classes anyway, is it worth keeping OperationVariable just for a bit more backwards compatibility? And that is assuming OperationVariable changes in the future, which we don't know yet.

[s-heppner]

Fixed in #151