From: Dirk Gerrits (dirk_at_[hidden])
Date: 2003-03-09 15:45:03
Dirk Gerrits wrote:
> Jaap Suter wrote:
>
>> Hi,
>>
>> In my own meta-programming I tend to use a lot of static_asserts and
>> concept
>> checks. However, these do have a negative impact on my compile-times.
>> Take,
>> for example, a meta-function that takes a type-list as its parameter.
>> Assume
>> a pre-condition is that the list may not be empty. What I can do is:
>>
>> BOOST_STATIC_ASSERT( (mpl::not_< typename mpl::empty< List >::type
>>
>>> ::type::value) );
>>
>>
>>
>> And while this is a good thing most of the time, sometimes I would
>> like to
>> disable these checks so my compiles go faster. What is the recommended
>> way
>> of doing this?
>>
>> 1. Using a define:
>>
>> #ifndef UID_DO_CHECKS
>> BOOST_STATIC_ASSERT( (mpl::not_< typename mpl::empty< List >::type
>>
>>> ::type::value) );
>>
>>
>> #endif
>>
>> 2. Using a boolean trait or policy, that is passed to a meta-if
>> statement:
>>
>> BOOST_STATIC_ASSERT( (
>> mpl::apply_if< check_policy,
>> mpl::not_< typename mpl::empty< List >::type >::type::value,
>> true_ >::type::value ));
>>
>> 3. Other ideas?
>
>
> I'd say something like:
>
> #ifdef STATIC_NDEBUG
> # define BOOST_STATIC_ASSERT2(e) BOOST_STATIC_ASSERT(e)
> #else
> # define BOOST_STATIC_ASSERT2(e) (void(e))
> #endif
>
> Analogous to <cassert>.
Argh, the if and else branches should be reversed of course. You've
gotta love negative logic. ;)
Dirk Gerrits