Re: Searching OO Associations with RDBMS Persistence Models
Date: 19 Jun 2006 19:33:38 -0700
Message-ID: <1150770818.309746.45280_at_b68g2000cwa.googlegroups.com>
Robert Martin wrote:
> Cimode wrote:
> > How did you define *identity* on these semantic elements
> > without a key? What other mechanism of identification
> > have you used to coherently identify these semantic
> > elements? Do you suppose they is a need to distinguish
> > them or not?
> >
> > Just curious.
>
> An object has an intrinsic identity within the computer.
> You could think of this identity as the pointer to the
> object; but this is an approximation at best. Some
> languages expose the numeric value of that pointer, and
> some don't. Others allow an object to have more than one
> address. So, although an object is a tuple, the notion of
> a key as one of the fields of the tuple that uniquely
> identifies the tuple, is not part of OO.
Aren't /this/ in C++ and /self/ in SmallTalk conceptually fields? (Albeit second-class fields.) And the fact that in C++ an object can have multiple numerical addresses is just an implementation artifact. Suppose this were not the case. In other words, suppose a hypothetical language in which every object had a unique numerical address. Would that still be an approximation of indentity? If so why?
- Keith -- Fraud 6