refactor(functors) remove invalid_value
NEEDS: Analysis!902 (merged) DaVinci!720 (merged)
This removes the constexpr invalid_value
members and makes those functors use Functors::Optional
It also implements the proposal in this comment by @graven.
So, we now have a VALUE_OR(val)
functor which can be chained to a functor that return a Functors::Optional
and it will return the contained value of the optional or the default value val
if the optional is emtpy.
Draft until FunTuple is adapted.
@amathad this is the Rec part we need to remove the invalid_value
stuff.
Also see related DaVinci#58 (closed)
Edited by Christoph Hasse