Significant digits REPL representation (#30)

shows only significant digits of `Measurement` objects in the REPL.
Relates to #5 as a proof of concept.

.gitignore

@@ -1,3 +1,4 @@
+*.swp
 *.jl.cov
 *.jl.*.cov
 *.jl.mem

src/Measurements.jl

@@ -101,6 +101,16 @@ measurement
 # Type representation
 Base.show(io::IO, measure::Measurement) =
     print(io, measure.val, get(io, :compact, false) ? "±" : " ± ", measure.err)
+function Base.show(io::IO, ::MIME"text/plain", m::Measurement )
+    if get( io, :limit, false )
+       print(io, round( m.val, digits = -Base.hidigit(m.err, 10) + 2),
+             get(io, :compact, false) ? "±" : " ± ",
+             round(m.err, sigdigits=2))
+    else
+       print(io, m)
+    end # if
+end
+
 Base.show(io::IO, ::MIME"text/latex", measure::Measurement) =
     print(io, "\$", measure.val, " \\pm ", measure.err, "\$")
 for mime in (MIME"text/x-tex", MIME"text/x-latex")
@@ -122,6 +132,22 @@ function Base.show(io::IO, measure::Complex{<:Measurement})
     end
     print(io, "(", i, ")im")
 end
+function Base.show(io::IO, mtype::MIME"text/plain", measure::Complex{<:Measurement})
+    r, i = reim(measure)
+    compact = get(io, :compact, false)
+    print(io, "(")
+    show(io, mtype, r)
+    print(io, ")")
+    if signbit(i) && !isnan(i)
+        i = -i
+        print(io, compact ? "-" : " - ")
+    else
+        print(io, compact ? "+" : " + ")
+    end
+    print(io, "(")
+    show(io, mtype, i)
+    print(io, ")im")
+end
 # This is adapted from base/show.jl for Complex type.
 function Base.alignment(io::IO, measure::Measurement)
     m = match(r"^(.*[\±])(.*)$", sprint(show, measure, context=io, sizehint=0))

test/runtests.jl

@@ -545,6 +545,13 @@ end
 end
 
 @testset "Type representation" begin
+    ww = -0.5345 ± 0.03123
+    zz = ww * (1 + im)
+    # test pretty printing at the REPL
+    @test repr("text/plain", ww, context=IOContext(stdout,:limit=>true,:compact=>true)) == "-0.534±0.031"
+    @test repr("text/plain", ww, context=:limit=>true) == "-0.534 ± 0.031"
+    @test repr("text/plain", zz, context=IOContext(stdout,:limit=>true,:compact=>true)) == "(-0.534±0.031)-(0.534±0.031)im"
+    @test repr("text/plain", zz, context=:limit=>true) == "(-0.534 ± 0.031) - (0.534 ± 0.031)im"
     @test repr("text/plain", [w 10x; 100y 1000w]) ==
         "2×2 Array{Measurement{Float64},2}:\n  -0.5±0.03    30.0±1.0 \n 400.0±20.0  -500.0±30.0"
     @test repr("text/plain", complex(x, w)) == "(3.0 ± 0.1) - (0.5 ± 0.03)im"