title: C# Multiple generic constraints
body: <p>I was wondering if it is possible to add multiple generic constraints?</p>
  
  <p>I have an Add method that takes an Object (Either Email, Phone or Address), so i was thinking something like:</p>
  
  <pre><code>public void Add&lt;T&gt;(T Obj) 
      where T : Address
      where T : Email
      where T : Phone
  {
      if (Obj is Address)
          m_Address.Add(Obj as Address);
      else if (Obj is Email)
          m_Email.Add(Obj as Email);
      else
          m_Phone.Add(Obj as Phone);
  }
  </code></pre>
  
  <p>But I keep getting:</p>
  
  <p><code>"A constraint clause has already been specified for type parameter 'T'. All of the constraints for a type parameter must be specified in a single where clause."</code></p>