make general case error and AbstractChar work

Author: Roger-luo

src/Measurements.jl

@@ -60,21 +60,19 @@ function Measurement(val::V, err::E, tag::UInt64,
     return Measurement(T(val), T(err), tag, Derivatives{T}(der))
 end
 Measurement{T}(x::Measurement{S}) where {T,S} = convert(Measurement{T}, x)
-Measurement{T}(x::S) where {T,S} = convert(Measurement{T}, x)
+Measurement{T}(x::S) where {T,S <: Real} = convert(Measurement{T}, x)
 
 # disambiguities
 Measurement{T}(x::S) where {T, S<:Rational} = convert(Measurement{T}, x)
 Measurement{T}(x::S) where {T, S<:Complex} = convert(Measurement{T}, x)
 Measurement{T}(x::S) where {T, S<:Base.TwicePrecision} = convert(Measurement{T}, x)
 Measurement{T}(x::S) where {P, T, S<:Rational{P}} = convert(Measurement{T}, x)
+Measurement{T}(x::S) where {T, S <: AbstractChar} = convert(Measurement{T}, x)
 
-
-function Measurement{T}(::S) where {T, S<:AbstractChar}
+function Measurement{T}(::S) where {T, S}
     throw(ArgumentError("cannot convert `$S` to `Measurement{$T}`"))
 end
 
-
-
 # Functions to quickly create an empty Derivatives object.
 @generated empty_der1(x::Measurement{T}) where {T<:AbstractFloat} = Derivatives{T}()
 @generated empty_der2(x::T) where {T<:AbstractFloat} = Derivatives{x}()

src/conversions.jl

@@ -24,6 +24,8 @@ Base.convert(::Type{Measurement{T}}, a::Real) where {T<:AbstractFloat} =
     measurement(T(a))::Measurement{T}
 Base.convert(::Type{Measurement{T}}, a::Base.TwicePrecision) where {T<:AbstractFloat} =
     measurement(T(a))::Measurement{T}
+Base.convert(::Type{Measurement{T}}, a::AbstractChar) where {T<:AbstractFloat} =
+    measurement(T(a))::Measurement{T}
 
 function Base.convert(::Type{Measurement{T}}, a::Complex) where {T}
     if isreal(a)

test/runtests.jl

@@ -109,6 +109,7 @@ end
     @test convert(Measurement{Float64}, 1+0im) ≈ 1.0±0.0
     @test_throws InexactError convert(Measurement{Float64}, 1+1im)
     @test convert(Measurement{Float64}, Base.TwicePrecision(1.0, 0.0)) ≈ 1.0±0.0
+    @test convert(Measurement{Float64}, 'a') ≈ Float64('a') ± 0.0
 end
 
 @testset "Comparisons and Tests" begin