
Boost : 
From: joaquin_at_[hidden]
Date: 20080709 05:24:30
Daryle Walker escribió:
> On Jul 9, 2008, at 3:02 AM, joaquin_at_[hidden] wrote:
>
[...]
>> You can use boost::mpl::equal to test this:
>>
>> BOOST_STATIC_ASSERT
>> ( (boost::mpl::equal<distinct_integral_bit_counts,
>> boost::mpl::list_c<int, 8, 16, 32> >::value) );
>> }
>>
>> Other than that, your type_to_digit_count is perfectly lambda
>> cabable AFAICS. HTH,
>>
>
> Thanks. I switched to mpl::equal and it compiled. I later switched
> to BOOST_MPL_ASSERT. (Remember to take _out_ the "::value" part!) I
> originally had the "integral_c" part of "type_to_digit_count" as a
> member called "type," instead of as a base class, then I switched
> back and forth. Both ways work. Why is that?
Because integral_c (and all other integral constant types in Boost.MPL)
evaluates to itself,
that is, it has the form:
template<typename T, T N>struct integral_c
{
typedef integral_c<T,N> type;
...
};
> And which way is best
> (if they're not equally good, and without a better third alternative)?
>
I don't think it makes any difference in compile times or otherwise, but
deriving
from integral_c is terser and more MPLidiomatic.
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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