Five days from today: ttcal.Today() + ttcal.Period(years=5)

tests/test_addition.py

@@ -0,0 +1,65 @@
+# -*- coding: utf-8 -*-
+from __future__ import print_function
+import ttcal
+
+
+def test_period_cmp():
+    assert ttcal.Period(months=5) == ttcal.Period(months=5)
+    assert ttcal.Period(months=4) != ttcal.Period(months=5)
+    assert ttcal.Period(months=4) < ttcal.Period(months=5)
+    assert ttcal.Period(months=4) <= ttcal.Period(months=5)
+    assert ttcal.Period(months=5) > ttcal.Period(months=4)
+    assert ttcal.Period(months=5) >= ttcal.Period(months=4)
+
+
+def test_period_add():
+    print("1m =", ttcal.Period(months=1))
+    print("1m + 1m =", ttcal.Period(months=1) + ttcal.Period(months=1))
+    assert ttcal.Period(months=1) + ttcal.Period(months=1) == ttcal.Period(months=2)
+
+
+def test_add_month():
+    assert ttcal.Day(2020, 1, 30) + ttcal.Period(months=1) == ttcal.Day(2020, 2, 29)
+    assert ttcal.Day(2020, 1, 30) + ttcal.Period(months=2) == ttcal.Day(2020, 3, 30)
+    assert ttcal.Day(2020, 1, 30) + ttcal.Period(months=3) == ttcal.Day(2020, 4, 30)
+    assert ttcal.Day(2020, 1, 30) + ttcal.Period(months=4) == ttcal.Day(2020, 5, 30)
+    assert ttcal.Day(2020, 1, 30) + ttcal.Period(months=5) == ttcal.Day(2020, 6, 30)
+
+
+def test_add_year_leap():
+    assert ttcal.Day(2020, 2, 29) + ttcal.Period(years=1) == ttcal.Day(2021, 2, 28)
+    assert ttcal.Day(2020, 2, 29) + ttcal.Period(years=2) == ttcal.Day(2022, 2, 28)
+    assert ttcal.Day(2020, 2, 29) + ttcal.Period(years=3) == ttcal.Day(2023, 2, 28)
+    assert ttcal.Day(2020, 2, 29) + ttcal.Period(years=4) == ttcal.Day(2024, 2, 29)
+    assert ttcal.Day(2020, 2, 29) + ttcal.Period(years=5) == ttcal.Day(2025, 2, 28)
+
+
+def test_add_month_lastday():
+    jan1 = ttcal.Day(2020, 1, 1)
+    jan31 = ttcal.Day(2020, 1, 31)
+    feb29 = ttcal.Day(2020, 2, 29)
+    months1 = ttcal.Period(months=1)
+    months2 = ttcal.Period(months=2)
+    months3 = ttcal.Period(months=3)
+    months4 = ttcal.Period(months=4)
+    months5 = ttcal.Period(months=5)
+    years1 = ttcal.Period(years=1)
+
+    print("jan1 + 1month=", jan1 + months1)
+    assert jan1 + months1 == ttcal.Day(2020, 2, 1)
+    assert feb29 + years1 == ttcal.Day(2021, 2, 28)
+    assert feb29 + months1 == ttcal.Day(2020, 3, 29)
+    assert jan31 + months1 == feb29
+    assert jan31 + months2 == ttcal.Day(2020, 3, 31)
+    assert jan31 + months3 == ttcal.Day(2020, 4, 30)
+    assert jan31 + months4 == ttcal.Day(2020, 5, 31)
+    assert jan31 + months5 == ttcal.Day(2020, 6, 30)
+
+    # assert ttcal.Period(months=1) + ttcal.Period(months=1) == ttcal.Period(months=2)
+
+    print("feb29 + months1 + months1 = ", feb29 + (months1 + months1))
+    assert feb29 + (months1 + months1) == ttcal.Day(2020, 4, 29)
+
+    print("(d + 1m) + 1m =", (feb29 + months1) + months1)
+    assert feb29 + months1 == ttcal.Day(2020, 3, 29)
+    assert (feb29 + months1) + months1 == ttcal.Day(2020, 4, 29)

ttcal/__init__.py

@@ -4,7 +4,7 @@
 """
 __version__ = '1.0.6'
 from .day import Day, Days, Today
-from .duration import Duration
+from .duration import Duration, Period
 from .calfns import chop, isoweek
 from .month import Month
 from .week import Week

ttcal/day.py

@@ -6,7 +6,7 @@
 import re
 import six
 from .calfns import rangecmp, rangetuple
-from .duration import Duration
+from .duration import Duration, Period
 
 
 class fstr(str):
@@ -228,6 +228,8 @@ def datetuple(self):
         return self.year, self.month, self.day
 
     def __add__(self, n):
+        if isinstance(n, Period):
+            return n.add_to_day(Day, self)
         return Day.fromordinal(self.toordinal() + n)
 
     # make first and last properties, because

ttcal/duration.py

@@ -5,8 +5,44 @@
 import re
 
 
+class Period(object):
+    """A semantic time period which doesn't need to be of fixed duration,
+       e.g. a month or a year.
+    """
+    def __init__(self, years=0, months=0):
+        self.months = months + 12 * years
+
+    def add_to_day(self, cls, d):
+        ym = d.Month + self.months
+        return cls(ym.year, ym.month, min(d.day, ym.daycount))
+
+    def __repr__(self):
+        if self.months >= 12:
+            return "Period(%d years, %d months)" % divmod(self.months, 12)
+        else:
+            return "Period(%d months)" % self.months
+
+    def __add__(self, other):
+        return Period(months=self.months + other.months)
+
+    def __eq__(self, other):
+        return self.months == other.months
+
+    def __neq__(self, other):
+        return self.months != other.months
+
+    def __gt__(self, other):
+        return self.months > other.months
+
+    def __ge__(self, other):
+        return self.months >= other.months
+
+    def __lt__(self, other):
+        return self.months < other.months
+
+
 class Duration(datetime.timedelta):
-    """A duration of time.
+    """A fixed duration of time.
     """
 
     @classmethod