Re: General semantics

On 24 mei, 16:03, r..._at_raampje.lan (Reinier Post) wrote:
> paul c wrote:
> I know the term OID only from some database literature, in which it is
> used for such generated values.  In OO programming, a distinction can
> be made between pointers, which are addresses in memory and which can
> be meaningfully added to, and references, which are not and on which
> the only meaningful operation is equality comparison.

> References are in between pointers and OIDs.

I recognize the importance of the concept of "not using the actual physical memory address as the means of identification of any object". It gets in the way of memory managers that need to relocate stuff.

So I recognize the concept that _inside_ an OO programming machine, it is useful to have a kind of mapping table that acts as the sole point of contact for any stuff that needs to access/wants to manipulate actual physical addresses. I also recognize the concept of calling the key in such a table a "reference" and the mapped value in such a table a "pointer".

That said, and assuming that is also what you meant, and noting that there can be several distinct references mapping to the same pointer value,

I'd like you to explain to me what exactly the usefulness is of "equality comparison of references", which I interpret to mean "equality of the key value in said mapping table".

And I'd like you to explain to me how the dereferencing operator on such a reference is totally unimportant. Which is indeed what is implied by your claim that "the only meaningful operation is equality comparison".

I say the only meaningful operation on reference types is dereferencing. Received on Wed May 26 2010 - 11:38:40 CEST