Make digits a keyword argument to round

In Julia 0.7, the digits positional argument to `round` was deprecated
in favor of a `digits=` keyword argument. This introduces a similar
change here.

README.md

@@ -132,7 +132,7 @@ Inequality:
 
 Rounding:
 
-    julia> round(decimal(3.1415), 2)
+    julia> round(decimal(3.1415), digits=2)
     Decimal(0,314,-2)
 
     julia> string(ans)

src/Decimals.jl

@@ -4,14 +4,14 @@
 __precompile__()
 
 module Decimals
-    import Base: ==, +, -, *, /, <, float, norm, inv
+    import Base: ==, +, -, *, /, <, float, norm, inv, round
 
     export Decimal,
            decimal,
            decimal,
            number
 
-    DIGITS = 20
+    const DIGITS = 20
 
     # Numerical value: (-1)^s * c * 10^q
     struct Decimal <: Real

src/norm.jl

@@ -11,7 +11,7 @@ function Base.normalize(x::Decimal; rounded::Bool=false)
     if rounded
         Decimal(x.s, abs(c), q)
     else
-        round(Decimal(x.s, abs(c), q), DIGITS; normal=true)
+        round(Decimal(x.s, abs(c), q), digits=DIGITS, normal=true)
     end
 end
 

src/round.jl

@@ -1,11 +1,13 @@
 # Rounding
-function Base.round(x::Decimal, dpts::Int=0; normal::Bool=false)
-    shift = BigInt(dpts) + x.q
+function round(x::Decimal; digits::Int=0, normal::Bool=false)
+    shift = BigInt(digits) + x.q
     if shift > BigInt(0) || shift < x.q
         (normal) ? x : normalize(x, rounded=true)
     else
-    c = Base.round(x.c / BigInt(10)^(-shift))
-    d = Decimal(x.s, BigInt(c), x.q - shift)
-    (normal) ? d : normalize(d, rounded=true)
+        c = Base.round(x.c / BigInt(10)^(-shift))
+        d = Decimal(x.s, BigInt(c), x.q - shift)
+        (normal) ? d : normalize(d, rounded=true)
     end
 end
+
+@deprecate round(x::Decimal, dpts::Int; normal::Bool=false) round(x, digits=dpts, normal=normal)

test/test_round.jl

@@ -3,14 +3,13 @@ using Compat.Test
 
 @testset "Rounding" begin
 
-@test round(Decimal(7.123456), 0) == Decimal(7)
-@test round(Decimal(7.123456), 2) == Decimal(7.12)
-@test round(Decimal(7.123456), 3) == Decimal(7.123)
-@test round(Decimal(7.123456), 5) == Decimal(7.12346)
-@test round(Decimal(7.123456), 6) == Decimal(7.123456)
+@test round(Decimal(7.123456), digits=0) == Decimal(7)
+@test round(Decimal(7.123456), digits=2) == Decimal(7.12)
+@test round(Decimal(7.123456), digits=3) == Decimal(7.123)
+@test round(Decimal(7.123456), digits=5) == Decimal(7.12346)
+@test round(Decimal(7.123456), digits=6) == Decimal(7.123456)
 
-@test round(0.123, 1) == 0.1
-@test round.([0.1111 0.2222 0.8888], 2) == [0.11 0.22 0.89]
+@test round.(Decimal.([0.1111, 0.2222, 0.8888]), digits=2) == Decimal.([0.11, 0.22, 0.89])
 
 function tet()
     a = parse(Decimal, "1.0000001")