From c87f1a5861e258e2188fad9363cca7522ac93aaf Mon Sep 17 00:00:00 2001
From: Alexander Barth <barth.alexander@gmail.com>
Date: Mon, 28 Dec 2020 16:52:23 +0100
Subject: [PATCH] convertion when substracting dates

---
 Project.toml      | 2 +-
 src/CFTime.jl     | 9 +++++++++
 test/test_time.jl | 6 ++++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index a3b864a..43cadac 100644
--- a/Project.toml
+++ b/Project.toml
@@ -3,7 +3,7 @@ uuid = "179af706-886a-5703-950a-314cd64e0468"
 keywords = ["time", "calendar", "netcdf", "climate and forecast conventions", "oceanography", "meteorology", "climatology", "opendap"]
 license = "MIT"
 desc = "Julia library for decoding time units conforming to the Climate and Forecasting (CF) netCDF conventions"
-version = "0.1.0"
+version = "0.1.1"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
diff --git a/src/CFTime.jl b/src/CFTime.jl
index e4b1140..8c4a151 100644
--- a/src/CFTime.jl
+++ b/src/CFTime.jl
@@ -394,6 +394,15 @@ pattern given in the `format` string.
 end
 
 
+-(dt1::Union{DateTimeStandard,DateTimeJulian,DateTimeProlepticGregorian},
+  dt2::DateTime) = DateTime(dt1) - DateTime(dt2)
+
+-(dt1::Union{DateTimeStandard,DateTimeJulian,DateTimeProlepticGregorian},
+  dt2::Union{DateTimeStandard,DateTimeJulian,DateTimeProlepticGregorian}) = DateTime(dt1) - DateTime(dt2)
+
+-(dt1::DateTime,
+  dt2::Union{DateTimeStandard,DateTimeJulian,DateTimeProlepticGregorian}) = DateTime(dt1) - DateTime(dt2)
+
 
 
 """
diff --git a/test/test_time.jl b/test/test_time.jl
index 55fc26a..76475ce 100644
--- a/test/test_time.jl
+++ b/test/test_time.jl
@@ -447,3 +447,9 @@ dt = @test_logs (:warn,r"Time zones are currently not supported.*") begin
 end
 data2 = CFTime.timeencode(dt,"days since 2000-01-01 00:00:00+00:00",DateTime360Day)
 @test data == data2
+
+
+# convertion when substracting dates
+@test DateTimeStandard(2000,1,1) - DateTime(2000,1,1) == Dates.Day(0)
+@test DateTime(2000,1,1) - DateTimeStandard(2000,1,1) == Dates.Day(0)
+@test DateTimeStandard(2000,1,1) - DateTimeProlepticGregorian(2000,1,1) == Dates.Day(0)