Re: [boost] a safe integer library

On 1/12/16 1:32 PM, Brook Milligan wrote:

On Jan 12, 2016, at 1:50 PM, Robert Ramey wrote:

It seems that the best correspondence might be something like the following:

typedef safe_int narrow_type; int x = { /* potentially something large */ }; if (checked::cast(x).no_exception()) { do_something_with_small_values(); } else { do_something_with_large_values(); }

Is that the correct semantics?

Looks OK. Should I be worried about the following comment from your docs: "Note that this type is an internal feature of the library and shouldn't be exposed to library users because it has some unsafe behavior.”? That seems worrisome and was a reason this did not register earlier. I don't remember what I was thinking when I wrote that. But it might be that I didn't want users to use the function without checking the return value.

This solution suggests that wrapping this particular construct in something that is unambiguously safe would be a good idea:

template < typename R, typename T > bool is_convertible<R>(T const& t) { return checked_cast<R>(t).no_exception(); }

Does that make sense?

I'd have to think about it. but it looks OK. BTW there is a function in mpl "is_convertible" which implements this behvaior at compiler time - not runtime as here. So you might want to change the name

Cheers, Brook

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