Add methods for iseven, isodd (#829)

Author: sostock

src/Unitful.jl

@@ -10,6 +10,7 @@ import Base: sin, cos, tan, asin, acos, atan, sinh, cosh, tanh, asinh, acosh, at
              sinpi, cospi, sinc, cosc, cis, cispi, sincos
 import Base: eps, mod, rem, div, fld, cld, divrem, trunc, round, sign, signbit
 import Base: isless, isapprox, isinteger, isreal, isinf, isfinite, isnan
+import Base: iseven, isodd
 import Base: copysign, flipsign
 import Base: prevfloat, nextfloat, maxintfloat, rat, step
 import Base: length, float, last, one, oneunit, zero, range

src/quantities.jl

@@ -314,8 +314,10 @@ end
 _dimerr(f) = error("$f can only be well-defined for dimensionless ",
         "numbers. For dimensionful numbers, different input units yield physically ",
         "different results.")
-isinteger(x::AbstractQuantity) = _dimerr(isinteger)
-isinteger(x::DimensionlessQuantity) = isinteger(uconvert(NoUnits, x))
+for f in [:isinteger, :iseven, :isodd]
+    @eval $f(x::AbstractQuantity) = _dimerr($f)
+    @eval $f(x::DimensionlessQuantity) = $f(uconvert(NoUnits, x))
+end
 
 _rounderr() = error("specify the type of the quantity to convert to ",
     "when rounding quantities. Example: round(typeof(1u\"m\"), 137u\"cm\").")

test/runtests.jl

@@ -911,6 +911,20 @@ Base.:(<=)(x::Issue399, y::Issue399) = x.num <= y.num
         @test_throws ErrorException isinteger(1.0m)
         @test isinteger(1.4m/mm)
         @test !isinteger(1.4mm/m)
+        @test_throws ErrorException iseven(1.0m)
+        @test iseven(2rad)
+        @test !iseven(1rad)
+        if hasmethod(iseven, (Float64,))
+            @test iseven(0.5m/mm)
+            @test !iseven(0.125m/mm)
+        end
+        @test_throws ErrorException isodd(1.0m)
+        @test isodd(1rad)
+        @test !isodd(2rad)
+        if hasmethod(isodd, (Float64,))
+            @test isodd(0.125m/mm)
+            @test !isodd(0.5m/mm)
+        end
         @test isfinite(1.0m)
         @test !isfinite(Inf*m)
         @test isnan(NaN*m)