add Printf support (#772)

Author: aplavin

Project.toml

@@ -13,11 +13,13 @@ Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 InverseFunctions = "3587e190-3f89-42d0-90ee-14403ec27112"
+Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 
 [extensions]
 ConstructionBaseUnitfulExt = "ConstructionBase"
 ForwardDiffExt = "ForwardDiff"
 InverseFunctionsUnitfulExt = "InverseFunctions"
+PrintfExt = "Printf"
 
 [compat]
 Aqua = "0.8"
@@ -26,6 +28,7 @@ Dates = "<0.0.1, 1"
 ForwardDiff = "0.10, 1"
 InverseFunctions = "0.1"
 LinearAlgebra = "<0.0.1, 1"
+Printf = "<0.0.1, 1"
 REPL = "<0.0.1, 1"
 Random = "<0.0.1, 1"
 Test = "<0.0.1, 1"
@@ -37,9 +40,10 @@ ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 InverseFunctions = "3587e190-3f89-42d0-90ee-14403ec27112"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 REPL = "3fa0cd96-eef1-5676-8a61-b3b8758bbffb"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Aqua", "ConstructionBase", "ForwardDiff", "InverseFunctions", "LinearAlgebra", "Test", "Random", "REPL"]
+test = ["Aqua", "ConstructionBase", "ForwardDiff", "InverseFunctions", "LinearAlgebra", "Test", "Random", "REPL", "Printf"]

ext/PrintfExt.jl

@@ -0,0 +1,22 @@
+module PrintfExt
+
+using Printf
+using Unitful
+using Unitful: AbstractQuantity
+
+Printf.plength(f::Printf.Spec{<:Printf.Ints}, x::AbstractQuantity{<:Real}) = Printf.plength(f, ustrip(x)) + length(string(unit(x))) + Unitful.has_unit_spacing(unit(x))
+
+# separate methods for disambiguation
+Printf.fmt(buf, pos, arg::AbstractQuantity{<:Real}, spec::Printf.Spec{<:Printf.Floats}) = _fmt(buf, pos, arg, spec)
+Printf.fmt(buf, pos, arg::AbstractQuantity{<:Real}, spec::Printf.Spec{<:Printf.Ints}) = _fmt(buf, pos, arg, spec)
+
+function _fmt(buf, pos, arg, spec)
+    pos = Printf.fmt(buf, pos, ustrip(arg), spec)
+    if Unitful.has_unit_spacing(unit(arg))
+        pos = Printf.fmt(buf, pos, ' ', only((Printf.format"%c").formats))
+    end
+    pos = Printf.fmt(buf, pos, string(unit(arg)), only((Printf.format"%s").formats))
+    return pos
+end
+
+end

test/runtests.jl

@@ -1,5 +1,5 @@
 using Unitful
-using Test, LinearAlgebra, Random, ConstructionBase, InverseFunctions
+using Test, LinearAlgebra, Random, ConstructionBase, InverseFunctions, Printf
 import Unitful: DimensionError, AffineError
 import Unitful: LogScaled, LogInfo, Level, Gain, MixedUnits, Decibel
 import Unitful: FreeUnits, ContextUnits, FixedUnits, AffineUnits, AffineQuantity
@@ -1739,6 +1739,10 @@ Base.show(io::IO, ::MIME"text/plain", ::Foo) = print(io, "42.0")
     @test Base.alignment(stdout, 3.0dBm*s) == Base.alignment(stdout, 3.0) .+ (1, 7)
 end
 
+VERSION ≥ v"1.9.0" && @testset "printf" begin
+    @test (@sprintf "%f %d %.2f %05d" 1.23u"m" 123.4u"°" 0.1234u"W" 12.34u"km") == "1.230000 m 123° 0.12 W 00012 km"
+end
+
 @testset "DimensionError message" begin
     function errorstr(e)
         b = IOBuffer()