[boost] Re: Meta programming 'debug' mode.

From: Dirk Gerrits (dirk_at_[hidden])
Date: 2003-03-09 15:41:56

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>.

Regards,

Dirk Gerrits