Actually, I was talking about sub

I agree that you were talking about subs, which is off-topic and misleading. Especially considering you specifically emphasised open which is not sub, and its arguments aren't passed to it by value.

As for "crying foul" - that makes this sound like a fight.

I don't know where you got that idea, but it's not the case.

In my opinion, trying to understand why someone made a mistake is as important as correcting them.

Indeed. And it had nothing to do with passing by value.

Perhaps those aren't your goals?

My goal was to help the OP, to which you were doing a disservice by providing the wrong explanation.