Extend Base.tryparse (#112)

Author: giordano

NEWS.md

@@ -1,12 +1,15 @@
 # History of Measurements.jl
 
-## v2.7.0 (2021-??-??)
+## v2.7.0 (2021-12-28)
 
 ### New features
 
 * Support hashing of `Measurement` objects
   ([#103](https://github.com/JuliaPhysics/Measurements.jl/issues/103),
   [#104](https://github.com/JuliaPhysics/Measurements.jl/pull/104)).
+* New method `Base.tryparse(::Type{Measurement}, ::AbstractString)`
+  ([#110](https://github.com/JuliaPhysics/Measurements.jl/issues/110),
+  [#112](https://github.com/JuliaPhysics/Measurements.jl/pull/112)).
 
 ### Deprecations
 

src/parsing.jl

@@ -83,7 +83,7 @@ julia> measurement("-1234e-1")
 """
 measurement(str::AbstractString) = parse(Measurement{Float64}, str)
 
-function Base.parse(::Type{Measurement{T}}, str::S) where {T<:AbstractFloat, S<:AbstractString}
+function Base.tryparse(::Type{Measurement{T}}, str::S) where {T<:AbstractFloat, S<:AbstractString}
     m = match(rxp_error_with_parentheses, str)
     if m !== nothing # "123(45)e6"
         val_str::S, val_dec, err_str::S, err_dec_str, expn = m.captures
@@ -105,7 +105,7 @@ function Base.parse(::Type{Measurement{T}}, str::S) where {T<:AbstractFloat, S<:
                 val_str, err_str, val_dec, expn =
                     m.captures[1], "0", nothing, nothing
             else
-                throw(ArgumentError("cannot parse $(repr(str)) as Measurement{$T}"))
+                return nothing
             end
         end
     end
@@ -127,3 +127,9 @@ function Base.parse(::Type{Measurement{T}}, str::S) where {T<:AbstractFloat, S<:
     end
     return measurement(val, err)
 end
+
+function Base.parse(::Type{Measurement{T}}, str::S) where {T<:AbstractFloat, S<:AbstractString}
+    out = tryparse(Measurement{T}, str)
+    out === nothing && throw(ArgumentError("cannot parse $(repr(str)) as Measurement{$T}"))
+    return out
+end