Re: Call by reference vs. call by value

[dewar@cs.nyu.edu (Robert Dewar)]

Felaco said:

"That's a good question - just how does the compiler determine how to
pass array parameters where rep specs or packing applies?  Does it use
bit pointers, or does it just make a properly aligned copy and pass it
along?  If the LRM dictated that all arrays were passed by reference,
then the compiler could decide to use bit pointers (if the
architecture provided efficient means to do so) or it could just
resort to making a copy and passing a reference to it."

That's a common confusion, but it is quite wrong. Call by reference
is a semantic concept, it is not about passing pointers (the actual
mechanism might well involve pointer passing, but that's an implementation
level issue). Passing a pointer to a copy is NOT call by reference, but
rather call by value.

As for the first question, "Does it use bit pointers or does it just ..."
the answer to this question is yes!