Allow constructing measurement with symbol-like types

Author: LebedevRI

Project.toml

@@ -10,11 +10,13 @@ Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 RecipesBase = "3cdcf5f2-1ef4-517c-9805-6587b60abb01"
 Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
+SymbolicsBase = "13454fcc-48b2-433e-829a-0418001dc7cb"
 
 [compat]
 Calculus = "0.4.1, 0.5"
 RecipesBase = "0.6.0, 0.7, 0.8, 1.0"
 Requires = "0.5.0, 1"
+SymbolicsBase = "0.1.0"
 julia = "1"
 
 [extras]

src/Measurements.jl

@@ -21,6 +21,9 @@ __precompile__()
 
 module Measurements
 
+# We want to special-case symbolic variables, which requires detecting them.
+using SymbolicsBase
+
 # Calculus is used to calculate numerical derivatives in "@uncertain" macro.
 using Calculus
 using Statistics
@@ -91,9 +94,16 @@ function __init__()
 end
 
 measurement(x::Measurement) = x
-measurement(val::T) where {T<:AbstractFloat} = Measurement(val, zero(T), UInt64(0), empty_der2(val)) # FIXME
-measurement(val::Real) = measurement(float(val)) # FIXME
-function measurement(val::T, err::T) where {T<:AbstractFloat} # FIXME
+function measurement(val::T) where {T<:Real}
+    if !(T<:AbstractFloat) && !SymbolicsBase.issymbollike(val)
+        return measurement(float(val))
+    end
+    return Measurement(val, zero(T), UInt64(0), empty_der2(val))
+end
+function measurement(val::T, err::T) where {T<:Real}
+    if !(T<:AbstractFloat) && !SymbolicsBase.issymbollike(val)
+        return measurement(promote(float(val), float(err))...)
+    end
     newder = empty_der2(val)
     if iszero(err)
         Measurement{T}(val, err, UInt64(0), newder)
@@ -102,7 +112,7 @@ function measurement(val::T, err::T) where {T<:AbstractFloat} # FIXME
         return Measurement{T}(val, err, tag, Derivatives(newder, (val, err, tag)=>one(T)))
     end
 end
-measurement(val::Real, err::Real) = measurement(promote(float(val), float(err))...) # FIXME
+measurement(val::Real, err::Real) = measurement(promote(val, err)...)
 measurement(::Missing, ::Union{Real,Missing} = missing) = missing
 const ± = measurement