Allow conversions to/from Real for TimeTypes. Also add documentation …

…and tests.

base/dates/conversions.jl

@@ -5,8 +5,30 @@ Date(dt::TimeType) = convert(Date,dt)
 DateTime(dt::TimeType) = convert(DateTime,dt)
 Base.convert(::Type{DateTime},dt::Date) = DateTime(UTM(value(dt)*86400000))
 Base.convert(::Type{Date},dt::DateTime) = Date(UTD(days(dt)))
+"""
+ convert{T<:Real}(::Type{T}, dt::DateTime) -> T
+Converts a DateTime value `dt` to a number of type `T`. The returned value corresponds to the number of Rata Die milliseconds since epoch.
+See `convert(DateTime, x::Real)` for inverse.
+"""
 Base.convert{R<:Real}(::Type{R},x::DateTime) = convert(R,value(x))
+"""
+ convert{T<:Real}(::Type{T}, dt::Date) -> T
+Converts a Date value `dt` to a number of type `T`. The returned value corresponds to the number of Rata Die days since epoch.
+See `convert(Date, x::Real)` for inverse.
+"""
 Base.convert{R<:Real}(::Type{R},x::Date) = convert(R,value(x))
+"""
+ convert{T<:Real}(::Type{DateTime}, x::T) -> DateTime
+Converts a number of type `T` to a DateTime. `x` should be the number of Rata Die milliseconds since epoch.
+See `convert(Int64,dt::DateTime)` for inverse.
+"""
+Base.convert{R<:Real}(::Type{DateTime}, x::R) = DateTime(UTM(x))
+"""
+ convert{T<:Real}(::Type{Date}, x::T) -> Date
+Converts a number of type `T` to a Date. `x` should be the number of Rata Die days since epoch.
+See `convert(Int64,dt::Date)` for inverse.
+"""
+Base.convert{R<:Real}(::Type{Date}, x::R) = Date(UTD(x))
 
 @vectorize_1arg DateTime Date
 @vectorize_1arg Date DateTime
@@ -71,7 +93,7 @@ rata2datetime(days) = DateTime(yearmonthday(days)...)
 
 Returns the number of Rata Die days since epoch from the given `Date` or `DateTime`.
 """
-datetime2rata(dt::DateTime) = days(dt)
+datetime2rata(dt::TimeType) = days(dt)
 
 # Julian conversions
 const JULIANEPOCH = value(DateTime(-4713,11,24,12))

test/dates/conversions.jl

@@ -85,3 +85,18 @@ let dt = DateTime(1915,1,1,12)
  @test Dates.unix2datetime(unix) == dt
  @test Dates.julian2datetime(julian) == dt
 end
+
+# Conversions to/from numbers
+a = Dates.DateTime(2000)
+b = Dates.Date(2000)
+@test convert(Real,b) == 730120
+@test convert(Float64,b) == 730120.0
+@test convert(Int32,b) == 730120
+@test convert(Real,a) == 63082368000000
+@test convert(Float64,a) == 63082368000000.0
+@test convert(Int64,a) == 63082368000000
+@test convert(DateTime,63082368000000) == a
+@test convert(DateTime,63082368000000.0) == a
+@test convert(Date,730120) == b
+@test convert(Date,730120.0) == b
+@test convert(Date,Int32(730120)) == b

test/dates/types.jl

@@ -114,12 +114,7 @@ b = Dates.Date(2000)
 @test typemax(Dates.DateTime) - typemin(Dates.DateTime) == Dates.Millisecond(9223372017043199000)
 @test string(typemax(Dates.Date)) == "252522163911149-12-31"
 @test string(typemin(Dates.Date)) == "-252522163911150-01-01"
-@test convert(Real,b) == 730120
-@test convert(Float64,b) == 730120.0
-@test convert(Int32,b) == 730120
-@test convert(Real,a) == 63082368000000
-@test convert(Float64,a) == 63082368000000.0
-@test convert(Int64,a) == 63082368000000
+
 # Date-DateTime conversion/promotion
 @test Dates.DateTime(a) == a
 @test Dates.Date(a) == b
@@ -173,4 +168,3 @@ ms = Dates.Millisecond(1)
 @test Dates.Date(d,y) == Dates.Date(1,1,1)
 @test Dates.Date(d,m) == Dates.Date(1,1,1)
 @test Dates.Date(m,y) == Dates.Date(1,1,1)
-