[RFC] monkey patch setindex

Project.toml

@@ -4,7 +4,9 @@ version = "0.5.2"
 
 [deps]
 ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"
+Future = "9fa8497b-333b-5362-9e8d-4d0656e87820"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
+Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 
 [compat]
 ConstructionBase = "0.1, 1.0"

src/Setfield.jl

@@ -2,7 +2,13 @@ __precompile__(true)
 module Setfield
 using MacroTools
 using MacroTools: isstructdef, splitstructdef, postwalk
+using Requires: @require
 
+if VERSION < v"1.1-"
+    using Future: copy!
+end
+
+include("setindex.jl")
 include("lens.jl")
 include("sugar.jl")
 include("functionlenses.jl")
@@ -23,4 +29,11 @@ for n in names(Setfield, all=true)
     end
 end
 
+function __init__()
+    @require StaticArrays="90137ffa-7385-5640-81b9-e52037218182" begin
+        setindex(a::StaticArrays.StaticArray, args...) =
+            Base.setindex(a, args...)
+    end
+end
+
 end

src/lens.jl

@@ -7,7 +7,7 @@ export constructorof
 
 
 import Base: get
-using Base: setindex, getproperty
+using Base: getproperty
 
 """
     Lens

src/setindex.jl

@@ -0,0 +1,22 @@
+Base.@propagate_inbounds function setindex(args...)
+    Base.setindex(args...)
+end
+
+Base.@propagate_inbounds function setindex(xs::AbstractArray, v, I...)
+    T = promote_type(eltype(xs), typeof(v))
+    ys = similar(xs, T)
+    if eltype(xs) !== Union{}
+        copy!(ys, xs)
+    end
+    ys[I...] = v
+    return ys
+end
+
+Base.@propagate_inbounds function setindex(d0::AbstractDict, v, k)
+    K = promote_type(keytype(d0), typeof(k))
+    V = promote_type(valtype(d0), typeof(v))
+    d = empty(d0, K, V)
+    copy!(d, d0)
+    d[k] = v
+    return d
+end

test/perf.jl

@@ -42,7 +42,7 @@ function lens_set_i((obj, val, i))
 end
 
 function hand_set_i((obj, val, i))
-    @inbounds setindex(obj, val, i)
+    @inbounds Base.setindex(obj, val, i)
 end
 
 function benchmark_lens_vs_hand(b_lens::Benchmark, b_hand::Benchmark)

test/runtests.jl

@@ -1,5 +1,6 @@
 module TestSetfield
 
+include("test_setindex.jl")
 include("test_examples.jl")
 include("test_setmacro.jl")
 include("test_core.jl")

test/test_setindex.jl

@@ -0,0 +1,37 @@
+module TestSetindex
+using Setfield
+using Test
+
+"""
+    ==ₜ(x, y)
+
+Check that _type_ and value of `x` and `y` are equal.
+"""
+==ₜ(_, _) = false
+==ₜ(x::T, y::T) where T = x == y
+
+@testset "==ₜ" begin
+    @test 1 ==ₜ 1
+    @test !(1.0 ==ₜ 1)
+end
+
+@testset "setindex" begin
+    arr = [1,2,3]
+    @test_throws MethodError Base.setindex(arr, 10, 1)
+    @test Setfield.setindex(arr, 10, 1) == [10, 2, 3]
+    @test arr == [1,2,3]
+    @test @set(arr[1] = 10) == [10, 2, 3]
+    @test arr == [1,2,3]
+    @test Setfield.setindex(arr, 10.0, 1) ==ₜ Float64[10.0, 2.0, 3.0]
+
+    d = Dict(:a => 1, :b => 2)
+    @test_throws MethodError Base.setindex(d, 10, :a)
+    @test Setfield.setindex(d, 10, :a) == Dict(:a=>10, :b=>2)
+    @test d == Dict(:a => 1, :b => 2)
+    @test @set(d[:a] = 10) == Dict(:a=>10, :b=>2)
+    @test d == Dict(:a => 1, :b => 2)
+    @test Setfield.setindex(d, 30, "c") ==ₜ Dict(:a=>1, :b=>2, "c"=>30)
+    @test Setfield.setindex(d, 10.0, :a) ==ₜ Dict(:a=>10.0, :b=>2.0)
+end
+
+end