Merge pull request #1031 from FluxML/cl/params

construct Params with empty tuple

Author: CarloLucibello

Project.toml

@@ -1,6 +1,6 @@
 name = "Zygote"
 uuid = "e88e6eb3-aa80-5325-afca-941959d7151f"
-version = "0.6.16"
+version = "0.6.17"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/tools/idset.jl

@@ -3,18 +3,16 @@ struct IdSet{T} <: AbstractSet{T}
   IdSet{T}() where T = new(IdDict{T,Nothing}())
 end
 
-Base.eltype(::IdSet{T}) where T = T
+IdSet(xs) = IdSet{eltype(xs)}(xs)
 
 IdSet() = IdSet{Any}()
 
+IdSet{T}(xs) where T = isempty(xs) ? IdSet{T}() : push!(IdSet{T}(), xs...)
+
 Base.push!(s::IdSet{T}, x::T) where T = (s.dict[x] = nothing; s)
 Base.delete!(s::IdSet{T}, x::T) where T = (delete!(s.dict, x); s)
 Base.in(x, s::IdSet) = haskey(s.dict, x)
-
-IdSet{T}(xs) where T = push!(IdSet{T}(), xs...)
-
-IdSet(xs) = IdSet{eltype(xs)}(xs)
-
+Base.eltype(::IdSet{T}) where T = T
 Base.collect(s::IdSet) = Base.collect(keys(s.dict))
 Base.similar(s::IdSet, T::Type) = IdSet{T}()
 

test/interface.jl

@@ -82,6 +82,12 @@ using Zygote: Grads
     @test ps isa Params
     @test issetequal(ps, Set([y]))
   end
+
+  @testset "constructor with empty args" begin
+    @test length(Params()) == 0
+    @test length(Params(())) == 0
+    @test length(Params([])) == 0
+  end
 end
 
 @testset "Grads" begin