I don't think anyone really objects to unsigned_integer, though some question its utility. The problem seems to me to be the idea that it inherits from integer -- an almost classic example of misuse of inheritance. Pardon me if I lost the thread somewhere but that seems to be what is being proposed. As others have said, inheritance should represent ISA both in interface and conceptually. If unsigned_integer followed this relationship than there would be no argument here -- the negative of an unsigned_integer would be clearly and unambiguously defined -- it just wouldn't happen to be an unsigned_integer. But that seems to eliminate the point of having a separate unsigned_integer type. Inheriting unsigned_integer from integer means that I can never be sure that negating an integer (which might actually be an unsigned_integer) is a reasonable thing to do. VERY BAD DESIGN. Personally I would vote for unsigned_integer which does not inherit from integer, though I think that it is lower priority than infinite (more accurately, indefinite) precision (more accurately, "magnitude") integer. I do think that there is some use to an integral type that provides assurance that it is never negative. I would drop negate, and would include both a exception-throwing and a modular subtract. Just don't have it inherit from integer -- it makes integer useless except under tightly controlled circumstances (e.g., I could never use it as part of an API). Topher At 08:13 AM 6/1/2006, you wrote:
Daniel, Users that don't like the unsigned_integer and want to use integer although it will never become negative, are free to do so. But users that want to make sure that variables never become negative, but still want those variables to be really with infinite precision, have the option to use unsigned_integer. Regards, Maarten.
"Daniel Mitchell" <danmitchell@mail.utexas.edu> wrote in message news:200605311735.17167.danmitchell@mail.utexas.edu...
I know I'm entering this discussion a little late, so forgive me if this has already been said, but I fail to see the point of having an unsigned_integer. I understand that certain quantities are intrinsically non-negative and therefore the idea of an unsigned_integer has aesthetic value, but my experience with the built-in types is that unsigned integers create more problems than they solve. (I'm talking about subtraction and comparison to signed types.) An infinite precision signed integer can represent all the same values as an unsigned integer, so from a practical point of view, why bother with the unsigned type at all? It seems to me that it just introduces a lot of unnecessary complexity.
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