support more functions in constructorof (#89)

Now works with regular functions and non-closure anonymous functions as well.

Author: aplavin

Project.toml

@@ -1,7 +1,7 @@
 name = "ConstructionBase"
 uuid = "187b0558-2788-49d3-abe0-74a17ed4e7c9"
 authors = ["Takafumi Arakaki", "Rafael Schouten", "Jan Weidner"]
-version = "1.5.5"
+version = "1.5.6"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/functions.jl

@@ -6,6 +6,8 @@ struct FunctionConstructor{F} end
 _isgensym(s::Symbol) = occursin("#", string(s))
 
 @generated function (fc::FunctionConstructor{F})(args...) where F
+    isempty(args) && return Expr(:new, F)
+
     T = getfield(parentmodule(F), nameof(F))
     # We assume all gensym names are anonymous functions
     _isgensym(nameof(F)) || return :($T(args...))

test/runtests.jl

@@ -246,7 +246,7 @@ end
     end
 end
 
-@testset "Anonymous function constructors" begin
+@testset "default function constructors" begin
     function multiplyer(a, b)
         x -> x * a * b
     end
@@ -259,6 +259,10 @@ end
     multbc = @inferred constructorof(typeof(mult23))("b", "c")
     @inferred multbc("a")
     @test multbc("a") == "abc"
+
+    @test (@inferred constructorof(typeof(sin))()) === sin
+    f = x -> x^2
+    @test (@inferred constructorof(typeof(f))()) === f
 end
 
 struct Adder{V} <: Function