title: create ++ operator in VHDL
body: <p>I would like to have a new C++ style operator for the STD_LOGIC_VECTOR type. So far I managed to create and use the following function:</p>
  
  <pre><code>FUNCTION PLUS_ONE ( a : STD_LOGIC_VECTOR) RETURN STD_LOGIC_VECTOR is 
  BEGIN
      RETURN std_logic_vector( unsigned( a ) + 1);
  END FUNCTION;
  </code></pre>
  
  <p>now if i create this:</p>
  
  <pre><code>FUNCTION "++" ( a : STD_LOGIC_VECTOR) RETURN      STD_LOGIC_VECTOR is 
  BEGIN
      RETURN std_logic_vector( unsigned( a ) + 1);
  END FUNCTION;
  </code></pre>
  
  <p>ISE throws the following error:</p>
  
  <pre><code>"++" is not a predefined operator.
  </code></pre>
  
  <p>Now the question is, is it possible to create new operators in VHDL an I am missing something</p>