| enable_if(3) | enable_if(3) |
enable_if - function application predicate
#include <cfl/functions/enable_if.hpp>
template <typename...> struct P;
auto g = enable_if <P> (f);
static_assert ((P <F, U...>::value), "");
f (u...) == g (u...)
Auguments a function f of type F with a predicate P for conditional
application. When g is invoked with arguments u of type U, f is only
eligible for application when P <F, U...> is true.
Note how the function type F itself is an argument to the predicate. In the
general case, the predicate may require this to for instance check the return
type of the function f (u...).
Another function, only applicable when function and argument types fulfill the predicate.
enable_if is a container function.
Following the CFL naming conventions strictly, enable_if should really be
called fenable_if, as the predicate argument is a factory. The proper name is
not very pleasing to the eye though, and until constexpr lambda is more widely
implemented, this inconcistency is accepted in CFL.