Subject: Re: [boost] [review][constrained_value] Review ofConstrainedValueLibrary begins today
From: Jeff Flinn (TriumphSprint2000_at_[hidden])
Date: 2008-12-06 11:32:11
Robert Kawulak wrote:
>> From: vicente.botet
...
> We already have a single type that covers both static and dynamic constraints,
> so what is the point? Did I misunderstood something?
>
>> 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.
Another reviewer mentioned he saw a problem in the implementations use
of EBO. I can't find that posting, but I thought it was Paul Bristow or
John Maddock. Perhaps that explains the MSVC size issue.
Jeff