id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
3228	Error message and expandable connectors	anonymous	somebody	"Consider the following code:
{{{
package ExpandableConn
  model IntegConn
    Modelica.Blocks.Continuous.Integrator integrator;
    Conn conn;
  equation
    connect(integrator.u, conn.signal);
  end IntegConn;

  expandable connector Conn ""Control bus that is adapted to the signals connected to it""
    extends Modelica.Icons.SignalBus;
    annotation(Diagram(graphics));
  end Conn;

  model Master
    Conn conn;
    Modelica.Blocks.Sources.Step step(startTime = 0.5);
  equation
    connect(step.y, conn.signal);
  end Master;

  model Combined
    IntegConn integConn;
    Master master;
  equation
    connect(master.conn, integConn.conn);
  end Combined;
  annotation(uses(Modelica(version = ""3.2.1"")));
end ExpandableConn;
}}}

If we check model ""Combined"" I get 5 equations and 5 variables. Correct. 
Now let us change Master so that the signal name in the connector becomes wrong:

{{{
model Master
  Conn conn;
  Modelica.Blocks.Sources.Step step(startTime = 0.5);
equation
  connect(step.y, conn.signal_);
end Master;
}}}

When checking Combined we get the following message:

Class ExpandableConn.Combined has 6 equation(s) and 7 variable(s).
5 of these are trivial equation(s).
""

This is clearly because the name ""signal"" and ""signal_"" are different.
This is true but it is not enough: imagine the same behaviour on a real-life simulation with hundreds of equations. A message saying that we have, let's say 500 equations and 501 variables might be VERY discouraging.

However I suppose that the message can be much more selective: OM can understand that there is a variable that is taken from an expandable connector ""conn.signal"" that no other models has sent to that given connection set.

So I thing a better error message could be envisaged. Just as an example it could be something like the following one

ERROR: The input signal ""integrator.u"" is connected to the expandable connector signal ""conn.signal"" but no variable with this name is available in the given connection set
"	enhancement	new	normal	Future	*unknown*	trunk