Implement Base.zero(::Type{MA.Zero}) (#283)

jump-dev · Apr 24, 2024 · 3c94705 · 3c94705
1 parent cbf8d63
commit 3c94705
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Showing 2 changed files with 5 additions and 1 deletion.
diff --git a/src/rewrite.jl b/src/rewrite.jl
@@ -30,6 +30,10 @@ end
 
 struct Zero end
 
+# This method is called in various `promote_operation_fallback` methods if one
+# of the arguments is `::Zero`.
+Base.zero(::Type{Zero}) = Zero()
+
 ## We need to copy `x` as it will be used as might be given by the user and be
 ## given as first argument of `operate!!`.
 #Base.:(+)(zero::Zero, x) = copy_if_mutable(x)

diff --git a/test/rewrite.jl b/test/rewrite.jl
@@ -9,7 +9,7 @@ import MutableArithmetics as MA
 
 @testset "Zero" begin
     z = MA.Zero()
-    #@test zero(MA.Zero) isa MA.Zero
+    @test zero(MA.Zero) isa MA.Zero
     @test z + z isa MA.Zero
     @test z + 1 == 1
     @test 1 + z == 1