Remove change_parameters fallback implementation (#16) (#17)

* Remove change_parameters identity fallback

* Add test for parameter interface defaults

* Bump version: 0.2.4 -> 0.3.0

Project.toml

@@ -1,7 +1,7 @@
 name = "DftFunctionals"
 uuid = "6bd331d2-b28d-4fd3-880e-1a1c7f37947f"
 authors = ["Michael F. Herbst <info@michael-herbst.com>"]
-version = "0.2.4"
+version = "0.3.0"
 
 [deps]
 ComponentArrays = "b0b7db55-cfe3-40fc-9ded-d10e2dbeff66"

src/interface.jl

@@ -53,8 +53,10 @@ Generally the identifier of the functional will be changed to reflect the
 change in parameter values unless `keep_identifier` is true.
 To get the tuple of adjustable parameters and their current values check out
 [`parameters`](@ref). It is not checked that the correct parameters are passed.
+
+`change_parameters(f::Functional, params_new; keep_identifier=false)::Functional`
 """
-change_parameters(f::Functional, ::AbstractArray; keep_identifier=false) = f
+function change_parameters end
 
 # TODO These values are read-only for now and their defaults hard-coded for Float64
 """

test/runtests.jl

@@ -43,6 +43,14 @@ end
     end
 end
 
+@testset "Parameter interface defaults" begin
+    struct NewExchange <: Functional{:lda,:x}
+    end
+    f = NewExchange()
+    @test parameters(f) == ComponentArray{Bool}()
+    x = ComponentArray{Bool}()
+    @test_throws MethodError change_parameters(f, x)
+end
 
 @testset "LDA potential (without spin)" begin
     ρ     = [0.1, 0.2, 0.3, 0.4, 0.5]