Extend connection annotation text

[DagBruck]

Today we allow a single Text annotation on a connection line. This change generalizes that to allow more than one, for example to be able to specify both %first and %second on a connection.

[henrikt-ma]

There are two main reasons why we at Wolfram don't want to go in this direction:

• The GUI operation for moving the label to a different point on the connection line becomes complicated when there is more than one label (I'll not go into more details about why unless asked).
• We believe that what users might actally want instead of multiple labels at the connect-equation is the possibility to attach labels to a connector of a component instance.

Also, isn't it a bit controversial to introduce more top-level annotations which may occur more than once?

A label on a component instance's connector would be placed on the component declaration:

  Modelica.Blocks.Continuous.Integrator integrator annotation(
      Placement(transformation(origin = {-70, 30}, extent = {{-10, -10}, {10, 10}})),
      labels = {
        ConnectorLabel(id = "u", label = Text(string = "a")),
        ConnectorLabel(id = "y", label = Text(string = "v"))
      }
    );

At the moment, however, we are not pushing for something like ConnectorLabel, as we'd like to get more experience with how the current connection line label is and can be used.

[HansOlsson]

There are two main reasons why we at Wolfram don't want to go in this direction:

• The GUI operation for moving the label to a different point on the connection line becomes complicated when there is more than one label (I'll not go into more details about why unless asked).
• We believe that what users might actally want instead of multiple labels at the connect-equation is the possibility to attach labels to a connector of a component instance.

Also, isn't it a bit controversial to introduce more top-level annotations which may occur more than once?

We have some, and to me there are two issues:

• Some minor inconveniences when handling them, but here that is tied to adding a connection-line so I find it manageable.
• Their semantics. Here they are fairly independent with (hopefully) minimal interaction, as the goal isn't to add somewhat over-lapping texts, but texts at different indices - so I don't find the semantics that problematic.

To me the current texts are clearly tied to the connection - not to the connector. Or more specifically to the connection-end-points (plural even for one label: the text is placed at one side of the connection and uses the connector-sub-part from the other side).

For those cases it doesn't make sense to move them to a different point on the connection-line - and it doesn't make sense to view them as labels for the connectors, as the label is specific to the connection not to the connector (so I don't see a case for having the labels without the connections).

However, I haven't investigated when more than one text would be super-useful. Currently they are used when connecting a sub-part to an expandable connector, and in those cases one text suffices as you connect a sub-part to the whole, not two sub-parts.

[henrikt-ma]

Before engaging deeper in this discussion, I would like to see some compelling real-world use cases (with pictures) fulfilling:

• Need for multiple labels.
• Labels need to be associated with connection line rather than the connectors at the endpoints of the line.