----- Original Message ----- From: "Robert Kawulak" <robert.kawulak@gmail.com> To: <boost@lists.boost.org> Sent: Saturday, December 06, 2008 4:31 AM Subject: Re: [boost] [review][constrained_value] ReviewofConstrainedValueLibrary begins today
From: vicente.botet
I would prefer to have two separated hierarchies, one for constrained values that preserv its constraints, error handling, ... staticaly, and one for those tyhe constraint can be changed at runtime.
I wouldn't prefer to have two separate hierarchies with almost identical functionality and differing only in details.
Well we can have a single type that cover with the whole domain, but we will need more metaprogramming.
We already have a single type that covers both static and dynamic constraints, so what is the point? Did I misunderstood something?
I'm sorry. I didn't see that you provide already static constraints. >From the documentation it was not clear to me that with your library you can do bounded<int>::type dyn_v; change_lower_bound(v, -5); but not bounded_int<int, 0, 128>::type _v; change_lower_bound(v, -5); // do not compiles I supose that I've missed the difference between 'bounded_int' and 'bounded<int>' and that I have skipped this sentence in the documentation: "The trick is to "convert" a value into a type, i.e. create a type that can be converted to the desired type yielding the value" It would be great if the documentation state explicitly that change_lower_bound(v, -5); do not compiles for bounded_int. And why not find a better name for bounded_int.
I expect that a constrained integer will have the same size as an int, i.e. sizeof(int). Which is the size of an instance of the constrained class?
Here are some examples:
GCC 4.3.2:
4 = sizeof (int) 4 = sizeof (bounded_int<int, 0, 128>::type) 12 = sizeof (bounded<int, int, int>::type) 4 = sizeof (constrained<int, is_even>)
MSVC 8.0 SP1:
4 = sizeof (int) 8 = sizeof (bounded_int<int, 0, 128>::type) 20 = sizeof (bounded<int, int, int>::type) 8 = sizeof (constrained<int, is_even>)
I don't know why MSVC cannot opimise the size as well as GCC, but anyway the library allows for perfect size optimisation with some compilers.
I hope you will find how to solve this issue. This is exaclty what I was locking for, but it was no evident to me your library provided it already I see now that this is really a well designed library. Thanks, Vicente