title: Bytecode manipulation patterns
body: <p>What legitimate uses are there for bytecode manipulation and how people implement those bytecode manipulation based solutions in practice?</p>
  
  <p><strong>Update:</strong> I should have made it more clear that this question really is about what patterns and techniques people use to make their code fly with the help of bytecode manipulation.</p>
  
  <p>Something like aspect oriented programming that was already mentioned or building proxy objects on the fly and similar techniques.</p>