Please explain how either of those references could point to object a. I think that will help answer your question.
the variable one changes to point to object "b"
On line 6 one = two; here = is an assignment operator syntactically right-associative which assign right side value to left side variable
But that is all new information which wasn't available in your original question. You only supplied one line, which line made it impossible for one to equal a.
Pedro Esgueira wrote:. . .
reference one is pointing to object "a" on line 4
referencce two is pointing to object "b" on line 5. . .
reference is a reference It is neer an object.
And here is my doubt: when do I interpret a reference - as a reference, or as the underlying object?
No, you are not. That is like interpreting my address, 123 Campbell Street, as my house. The address tells you where the house is, but doesn't tell you anything about the house there.
In this case we are interpretingone as a reference, and two as the underlying object "b".
The structure of the language. If you know my address, you don't know that my door is green. It is possible to repaint the door blue, but that takes time. It is very quick to reassign something to a different reference. All you have to do is write
What forbids us to interpretone as the underlying object "a" and two as a reference? . . .