On Jan 12, 2016, at 1:50 PM, Robert Ramey <ramey@rrsd.com> wrote:
It's going to be a little trickier than that. One basic problem is that there more than two cases, yes, no, have to check at runtime.
Yes, but I expected this to boil down to one of two cases depending on policy: - yes, no, or fail to compile, or - yes, no (will compile but may or may not invoke a runtime check) I thought those were basically the options for any of the operations and that the difference was based upon the policy choice. Do I misunderstand?
The above return a "checked_result<interval_t>" - which is decribed in another part of the documentation. Basically its similar to "optional" so it either returns a valid new interval or an error condition which you can test for.
It seems that the best correspondence might be something like the following: typedef safe_int<int8_t> narrow_type; int x = { /* potentially something large */ }; if (checked::cast<narrow_type>(x).no_exception()) { do_something_with_small_values(); } else { do_something_with_large_values(); } Is that the correct semantics? 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. 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? Cheers, Brook