| glfn(3) | glfn(3) |
glfn - function forward adaptor
#include <cfl/functions/glfn.hpp>
#include <cfl/tuple/tuple.hpp>
#include <cfl/access/atK.hpp>
decltype ( tuple (0)) == tuple_c <int >;
decltype (glfn (tuple) (0)) == tuple_c <int &&>;
decltype ( getN <0> (tuple (0))) == int );
decltype (glfn (getN <0>) (tuple (0))) == int &&);
glfn is short for generalized lvalue function, and adapts a function to
return by the generalized lvalue category (as described by the C++ specification
in [basic.lval]), instead of using standard CFL storage (as described in
conventions). Such adaption is normally supported by
all CFL functions constructed from factories.
Normally, this is applicable when accessing or creating an inner value of a
container. A maybe familiar example from std of such a distinction is
make_tuple and forward_as_tuple.
glfn is primarily used to avoid constructing values and instead use
references, when the caller can guarantee object lifetimes from the context.
glfn is a shallow operation, and does not recursively descend into
container like prvalue and noxvalue.
Another function adapted to use glvalues instead of standard CFL storage. When
the argument function does not support such adaption, glfn is a no-op and the
argument is returned unchanged.
glfn is not a container function.
conventions(5), prfn(3), prvalue(3)