Project.toml

@@ -11,27 +11,31 @@ RecipesBase = "3cdcf5f2-1ef4-517c-9805-6587b60abb01"
 Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 
 [weakdeps]
+BaseType = "7fbed51b-1ef5-4d67-9085-a4a9b26f478c"
 Juno = "e5e0dc1b-0480-54bc-9374-aad01c23163d"
 RecipesBase = "3cdcf5f2-1ef4-517c-9805-6587b60abb01"
 SpecialFunctions = "276daf66-3868-5448-9aa4-cd146d93841b"
 Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
 
 [extensions]
+MeasurementsBaseTypeExt = "BaseType"
 MeasurementsJunoExt = "Juno"
 MeasurementsRecipesBaseExt = "RecipesBase"
 MeasurementsSpecialFunctionsExt = "SpecialFunctions"
 MeasurementsSymbolicsExt = "Symbolics"
 MeasurementsUnitfulExt = "Unitful"
 
 [compat]
+BaseType = "0.2"
 Calculus = "0.4.1, 0.5"
 RecipesBase = "0.6.0, 0.7, 0.8, 1.0"
 Requires = "0.5.0, 1"
 julia = "1.6"
 
 [extras]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
+BaseType = "7fbed51b-1ef5-4d67-9085-a4a9b26f478c"
 Juno = "e5e0dc1b-0480-54bc-9374-aad01c23163d"
 QuadGK = "1fd47b50-473d-5c70-9696-f719f8f3bcdc"
 RecipesBase = "3cdcf5f2-1ef4-517c-9805-6587b60abb01"
@@ -42,4 +46,4 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
 
 [targets]
-test = ["Aqua", "QuadGK", "RecipesBase", "SpecialFunctions", "Statistics", "Symbolics", "Test", "Unitful"]
+test = ["Aqua", "BaseType", "QuadGK", "RecipesBase", "SpecialFunctions", "Statistics", "Symbolics", "Test", "Unitful"]

ext/MeasurementsBaseTypeExt.jl

@@ -0,0 +1,13 @@
+module MeasurementsBaseTypeExt
+
+if isdefined(Base, :get_extension)
+    using Measurements: Measurement
+    import BaseType: base_numeric_type
+else
+    using ..Measurements: Measurement
+    import ..BaseType: base_numeric_type
+end
+
+base_numeric_type(::Type{<:Measurement{T}}) where {T} = base_numeric_type(T)
+
+end

src/Measurements.jl

@@ -113,7 +113,7 @@ Return a `Measurement` object with `val` as nominal value and `err` as
 uncertainty.  `err` defaults to 0 if omitted.
 
 The binary operator `±` is equivalent to `measurement`, so you can construct a
-`Measurement` object by explicitely writing `123 ± 4`.
+`Measurement` object by explicitly writing `123 ± 4`.
 
 If `val` is `missing`, `missing` is returned.
 """
@@ -135,6 +135,7 @@ end
 
 @static if !isdefined(Base, :get_extension)
     function __init__()
+        @require BaseType = "7fbed51b-1ef5-4d67-9085-a4a9b26f478c" include("../ext/MeasurementsBaseTypeExt.jl")
         @require Unitful="1986cc42-f94f-5a68-af5c-568840ba703d" include("../ext/MeasurementsUnitfulExt.jl")
         @require SpecialFunctions="276daf66-3868-5448-9aa4-cd146d93841b" include("../ext/MeasurementsSpecialFunctionsExt.jl")
         @require Juno="e5e0dc1b-0480-54bc-9374-aad01c23163d" include("../ext/MeasurementsJunoExt.jl")

src/derivatives-type.jl

@@ -11,7 +11,7 @@
 #
 ### Commentary:
 #
-# This file containes the definition of Derivatives type.  This is borrowed from
+# This file contains the definition of Derivatives type.  This is borrowed from
 # Base.ImmutableDict type (see base/dict.jl in Julia source code), introduced in
 # Julia 0.5.  `get' and `getindex' have methods different from those of the
 # standard Base.ImmutabileDict, otherwise Derivatives and Base.ImmutableDict

test/runtests.jl

@@ -1,4 +1,4 @@
-using Measurements, SpecialFunctions, QuadGK, Calculus
+using Measurements, SpecialFunctions, QuadGK, Calculus, BaseType
 using Test, LinearAlgebra, Statistics, Unitful, Printf, Aqua
 
 if !isdefined(Base,:get_extension)
@@ -1066,6 +1066,19 @@ end
     @test range(0±0, step=1±.1, length=10) isa StepRangeLen
 end
 
+@testset "Base type" begin
+    for T in (Float16, Float32, Float64)
+        x = Measurement{T}(1.0)
+        @test base_numeric_type(x) == T
+        @test base_numeric_type(typeof(x)) == T
+
+        # Should still work for nested types:
+        nested_x = x * u"m"
+        @test base_numeric_type(x) == T
+        @test base_numeric_type(typeof(x)) == T
+    end
+end
+
 @static if Base.VERSION >= v"1.9" # We only support Symbolics w/ Julia 1.9+.
   @testset "Symbolics" begin
     include("symbolics.jl")