Enable rational conversion for types that cannot represent the number…

… two (#49) * change promotion in rational conversion * Use twice in unsafe_rational Co-authored-by: Sebastian Stock <42280794+sostock@users.noreply.github.com> * update other constructors * Add test * Update test/customtypes.jl Co-authored-by: Sebastian Stock <42280794+sostock@users.noreply.github.com> --------- Co-authored-by: Sebastian Stock <42280794+sostock@users.noreply.github.com>
sostock · Mar 10, 2023 · 82a8348 · 82a8348 · jishnub · Mar 10, 2023
1 parent 215556a
commit 82a8348
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Showing 2 changed files with 13 additions and 3 deletions.
diff --git a/src/HalfIntegers.jl b/src/HalfIntegers.jl
@@ -50,19 +50,19 @@ HalfInteger(x::BigFloat) = BigHalfInt(x)
         if isinteger(x)
             Base.unsafe_rational(tx >> 1, one(tx))
         else
-            Base.unsafe_rational(tx, oftype(tx, 2))
+            Base.unsafe_rational(tx, twice(one(tx)))
         end
     end
     function (::Type{Rational{T}})(x::HalfInteger) where T
         tx = twice(x)
         if isinteger(x)
             Base.unsafe_rational(T, tx >> 1, one(tx))
         else
-            Base.unsafe_rational(T, tx, oftype(tx,2))
+            Base.unsafe_rational(T, tx, twice(one(tx)))
         end
     end
 else
-    (T::Type{<:Rational})(x::HalfInteger) = (tx=twice(x); T(tx,oftype(tx,2)))
+    (T::Type{<:Rational})(x::HalfInteger) = (tx=twice(x); T(tx,twice(one(tx))))
 end
 
 Base.ArithmeticStyle(::Type{<:HalfInteger}) = Base.ArithmeticWraps()

diff --git a/test/customtypes.jl b/test/customtypes.jl
@@ -9,6 +9,13 @@ MyHalfInt(x::MyHalfInt) = x
 HalfIntegers.half(::Type{MyHalfInt}, x) = MyHalfInt(half(HalfInt, x))
 HalfIntegers.twice(x::MyHalfInt) = twice(x.val)
 
+struct One <: Integer end
+Base.promote_rule(::Type{One}, ::Type{T}) where {T<:Number} = promote_type(Bool, T)
+Base.Int(::One) = 1
+Base.iseven(::One) = false
+Base.one(::One) = One()
+Base.:+(x::One, y::One) = 2
+
 @testset "Custom types" begin
     @testset "Construction" begin
         @test MyHalfInt(2.5) isa MyHalfInt
@@ -35,6 +42,9 @@ HalfIntegers.twice(x::MyHalfInt) = twice(x.val)
         @test_throws InexactError Integer(MyHalfInt(3/2))
         @test_throws InexactError Int(MyHalfInt(3/2))
         @test_throws InexactError UInt(MyHalfInt(-1))
+
+        @test Rational(half(One())) == 1//2
+        @test Rational{Int}(half(One())) == 1//2
     end
 
     @testset "Properties" begin