Re: [boost] safe integer library -- the scope

On 12/14/15 12:43 AM, Andrzej Krzemienski wrote:

Ok, now I think I understand the scope of the library. You give me the tool for representing a mathematical notion of an integral number within *some* limited range. The contract is:

You guarantee: 1. Either correct result or a compile time error or a run-time exception. 2. No memory management: you will only take the space of one scalar type.

I would (and have) phrase it differently. 1. Either correct result or a compile time error or a run-time exception. 2. Best runtime performance possible subject to 1. above. So "No memory management" isn't a fundamental principle, but rather implied by 2. above in our current machines.

I specify the range of the representable values. I can say: 1. "From -100 to +100", or 2. "Whatever range 'int' as on my machine".

If you look at the code you'll see something like template struct safe_base { ... }; template<T> using safe<T> = safe_base

;

But if I got it right, I would say that the choice of the name, and the interface do not indicate the intent as clear as they could. Imagine the following alternative interface:

small_int>; // range-based policy

I call this safe_integer_range<-100, 100> - I don't think that's significantly different.

small_int; // underlying-type-based policy

I'm not sure what this is meant to mean. But note than many of my tests and examples I often use something like the following to make this clearer template using short_int_t = safe_range<0, 32>;

In the first case, the user specifies the range, and the library can choose the best underlying type for the job.

that's what safe_... range does.

In the second case, the user chooses the underlying type, and this implies the range [numeric_limits<T>::min(), numeric_limits<T>::max()]

that's what safe<T> does. Robert Ramey