title: Modelica: Mixing connectors and direct inputs
body: <p>The following Modelica package - while neither being particularly useful nor interesting - does not yield any warnings.</p>
  
  <pre><code>package P
    connector C
      Real c;
    end C;
    model A
      input C x;
      output Real y;
    equation 
      y = x.c;
    end A;
    model B
      input C inp;
      output C out;
      A a;
    equation 
      a.x = inp;
      out.c = a.y;
    end B;
  end P;
  </code></pre>
  
  <p>However, when <code>A</code> does not use connectors as in the following case, there is a warning: <em>The following input lacks a binding equation: <code>a.x</code></em>. Clearly, there is a binding equation for <code>a.x</code>. Why is there such a warning?</p>
  
  <pre><code>package P
    connector C
      Real c;
    end C;
    model A
      input Real x;
      output Real y;
    equation 
      y = x;
    end A;
    model B
      input C inp;
      output C out;
      A a;
    equation 
      a.x = inp.c;
      out.c = a.y;
    end B;
  end P;
  </code></pre>