Re: [boost] Infinite precision integer draft

From: Sebastian Redl (sebastian.redl_at_[hidden])
Date: 2006-06-01 18:06:18

Marsh J. Ray wrote:

>Seems to me that, if the author is really set on using inheritance here, 
>integer should inherit from unsigned_integer, since integer can do 
>everything that an unsigned can do, but not vice-versa. Integer extends 
>unsigned with the ability to represent negative values and the result of 
>subtraction.
>  
>
No, that's not true. (See Scott Meyers, Effective C++, Item 35) If a 
signed integer IS-A unsigned integer, then all invariants of unsigned 
integer must hold true for signed integer - including the one about 
negative values. ("There's no such thing.")

Sebastian Redl