Roadmap with respect to `Base.@kwdef`

Much of the @with_kw functionality has been implemented in Base.@kwdef, see JuliaLang/julia#29316, which will go into Julia 1.1. Once Julia 1.1 has been release, this should be used in Parameters. The plan could be to keep the @with_kw macro which would use @kwdef internally and enhance it with its "missing" features (show, reconstruct, type specific unpack macros, auto-documentation, @asserts).

@kwdef only defines an outer constructor, whereas @with_kw defines both inner and outer. There seems to be a reason for that:

Parameters.jl/src/Parameters.jl

Line 518 in 870131f

# NOTE: The reason to have both outer and inner keyword

, but I'm not sure this still applies.

Maybe this relates:

I defined the following struct

@with_kw struct Vesicle{
                C<:Number, #Curvature
                AR<:Number, #Area
                VO<:Number, #Volume
                P<:Number, #Pressure
                T<:Number, #Tension
                L<:Number, #Length
                R<:Real,
                E<:Number, #Energy
              }
    m::C = zero(C)
    A::AR
    V::VO
    ΔP::P
    Σ::T
    u0::C
    u1::C
    S::L
    v::R
    κ::E = 8e-20u"J"
    function Vesicle(m::C, A::AR, V::VO, ΔP::P, Σ::T, u0::D, u1::D, S::L, v::R, κ::E) where {C,AR,VO,P,T,D,L,R,E}
        (mm, uu0,uu1) = promote(m,u0,u1)
        return new{typeof(mm),AR,VO,P,T,L,R,E}(mm, A, V, ΔP, Σ, uu0, uu1, S, v, κ)
    end # function
end # struct

but Vesicle(zeros(10)...) fails with a MethodError, while Base.@kwdef works fine.

A breaking change would probably be to fix #96 to be consistent with @kwdef. This would mean to deprecate the reconstruct-constructor (in favor of using Setfield.jl, probably).