Merge pull request #17 from tkf/NamedTupleConstructor

Type-stable constructorof(::Type{<:NamedTuple})(args...)

src/ConstructionBase.jl

@@ -72,6 +72,19 @@ T{Int64,Int64}(10, 2)
     getfield(parentmodule(T), nameof(T))
 end
 
+constructorof(::Type{<:Tuple}) = tuple
+constructorof(::Type{<:NamedTuple{names}}) where names =
+    NamedTupleConstructor{names}()
+
+struct NamedTupleConstructor{names} end
+
+@generated function (::NamedTupleConstructor{names})(args...) where names
+    quote
+        Base.@_inline_meta
+        $(NamedTuple{names, Tuple{args...}})(args)
+    end
+end
+
 function assert_hasfields(T, fnames)
     for fname in fnames
         if !(fname in fieldnames(T))
@@ -187,15 +200,5 @@ end
     )
 end
 
-@generated function setproperties(obj::NamedTuple, patch::NamedTuple)
-    # this function is only generated to force the following check
-    # at compile time
-    assert_hasfields(obj, fieldnames(patch))
-    Expr(:block,
-        Expr(:meta, :inline),
-        :(merge(obj, patch))
-    )
-end
-
 
 end # module

test/runtests.jl

@@ -12,6 +12,10 @@ end
     @inferred constructorof(AB{Int, Int})
     @test constructorof(AB{Int, Int})(1, 2) === AB(1,2)
     @test constructorof(AB{Int, Int})(1.0, 2) === AB(1.0,2)
+    @test constructorof(typeof((a=1, b=2)))(1.0, 2) === (a=1.0, b=2)
+    @test constructorof(NamedTuple{(:a, :b)})(1.0, 2) === (a=1.0, b=2)
+    @test constructorof(Tuple)(1.0, 2) === (1.0, 2)
+    @test constructorof(Tuple{Nothing, Missing})(1.0, 2) === (1.0, 2)
 end
 
 @testset "setproperties" begin