Handle ChainRulesCore via Pkg extension (#206)

Project.toml

@@ -1,13 +1,19 @@
 name = "LinearMaps"
 uuid = "7a12625a-238d-50fd-b39a-03d52299707e"
-version = "3.10.0"
+version = "3.10.1"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
+[weakdeps]
+ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
+
+[extensions]
+LinearMapsChainRulesCoreExt = "ChainRulesCore"
+
 [compat]
 ChainRulesCore = "1"
 julia = "1.6"

src/chainrules.jl → ext/LinearMapsChainRulesCoreExt.jl

@@ -1,3 +1,10 @@
+module LinearMapsChainRulesCoreExt
+
+using ChainRulesCore: unthunk, NoTangent, @thunk, @not_implemented
+import ChainRulesCore: rrule
+
+using LinearMaps
+
 function rrule(::typeof(*), A::LinearMap, x::AbstractVector)
     y = A*x
     function pullback(dy)
@@ -15,3 +22,6 @@ function rrule(A::LinearMap, x::AbstractVector)
     end
     return y, pullback
 end
+
+
+end # module ChainRulesCore

src/LinearMaps.jl

@@ -10,9 +10,6 @@ using SparseArrays
 
 import Statistics: mean
 
-using ChainRulesCore: unthunk, NoTangent, @thunk, @not_implemented
-import ChainRulesCore: rrule
-
 using Base: require_one_based_indexing
 
 abstract type LinearMap{T} end
@@ -354,7 +351,6 @@ include("conversion.jl") # conversion of linear maps to matrices
 include("show.jl") # show methods for LinearMap objects
 include("getindex.jl") # getindex functionality
 include("inversemap.jl")
-include("chainrules.jl") # AD rules through ChainRulesCore
 
 """
     LinearMap(A::LinearMap; kwargs...)::WrappedMap
@@ -424,4 +420,8 @@ LinearMap(A::MapOrVecOrMat, dims::Dims{2}; offset::Dims{2}) =
 LinearMap{T}(A::MapOrVecOrMat; kwargs...) where {T} = WrappedMap{T}(A; kwargs...)
 LinearMap{T}(f, args...; kwargs...) where {T} = FunctionMap{T}(f, args...; kwargs...)
 
+@static if !isdefined(Base, :get_extension)
+    include("../ext/LinearMapsChainRulesCoreExt.jl")
+end
+
 end # module

test/runtests.jl

@@ -1,7 +1,7 @@
 using Test, LinearMaps, Aqua
 
 @testset "code quality" begin
-    Aqua.test_all(LinearMaps)
+    Aqua.test_all(LinearMaps, project_toml_formatting=VERSION≥v"1.7")
 end
 
 include("linearmaps.jl")