Method parameters cannot be referred to by their symbol names

When a trigger method is compiled with debug information the symbolic names of the method parameters are available in the local variable table. In this case it should be possible to refer to the parameter or the method target (this) as per any local variable e.g. for method foo(int i, Foo foo) it should be possible to refer to $this, $i and $foo in the method body. This should not preclude using the conventional indexed references $0, $1, etc.