i1abstraction/

greatabel · greatabel · commit 28e2a668ca3f · 2018-06-24T21:59:57.000+08:00
diff --git a/Modular-Programming-with-Python/ch5Working with Module Patterns/i1abstraction/happy_hour.py b/Modular-Programming-with-Python/ch5Working with Module Patterns/i1abstraction/happy_hour.py
@@ -0,0 +1,58 @@
+# happy_hour.py
+#
+# This program demonstrates how to calculate "happy hour", where happy hour
+# takes place each day between 5 and 6 pm, except on Sundays, Christmas Day and
+# Easter.
+
+import datetime
+
+#############################################################################
+
+def is_happy_hour():
+    today = datetime.date.today()
+
+    easter_sunday = calc_easter_sunday(today.year)
+    easter_friday = easter_sunday - datetime.timedelta(days=2)
+
+    if today == easter_friday:
+        return False
+
+    if today.month == 12 and today.day == 25: # Christmas day.
+        return False
+
+    if today.weekday() == 6: # Sunday.
+        return False
+
+    if datetime.datetime.now().hour == 17: # 5pm.
+        return True
+
+    return False
+
+#############################################################################
+
+# The following function calculates Easter Sunday for a given year, returning a
+# datetime.date object.  This code is taken from:
+#
+#     http://code.activestate.com/recipes/576517
+
+def calc_easter_sunday(year):
+    a = year % 19
+    b = year // 100
+    c = year % 100
+    d = (19 * a + b - b // 4 - ((b - (b + 8) // 25 + 1) // 3) + 15) % 30
+    e = (32 + 2 * (b % 4) + 2 * (c // 4) - d - (c % 4)) % 7
+    f = d + e - 7 * ((a + 11 * d + 22 * e) // 451) + 114
+    month = f // 31
+    day = f % 31 + 1    
+    return datetime.date(year, month, day)
+
+#############################################################################
+
+if __name__ == "__main__":
+    # Testing code.
+
+    if is_happy_hour():
+        print("It's happy hour!")
+    else:
+        print("It's not happy hour.")
+
