Created pure function version of increment.

chapter-16/exercise-16.4.py

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+#!/usr/bin/env python
+# encoding: utf-8
+"""
+exercise-16.4.py
+
+Created by Terry Bates on 2014-07-05.
+Copyright (c) 2014 http://the-awesome-python-blog.posterous.com. All rights reserved.
+"""
+
+
+import sys
+import os
+from copy import copy
+
+class Time(object):
+    """Represents the time of day.
+
+        attributes: hour, minute, second
+    """
+
+def print_time(time_obj):
+    hour, minute, second = time_obj.hour, time_obj.minute, time_obj.second
+    # Use join to quickly print out string colon separated
+    if int(second) < 10:
+        second = '0' + str(second)
+
+    if int(minute) < 10:
+        minute = '0' + str(minute)
+
+    print ':'.join([str(hour), str(minute), str(second)])
+
+
+def compute_scalar_time(time_obj):
+    # We create fractional portions of the "hour" attribute
+    return time_obj.hour + (time_obj.minute / 60) + (time_obj.second / 3600)
+
+
+def is_after(time_obj_1, time_obj_2):
+    # Get attribute info from objects.
+    hour_1, minute_1, second_1 = time_obj_1.hour, time_obj_1.minute, time_obj_1.second
+    hour_2, minute_2, second_2 = time_obj_2.hour, time_obj_2.minute, time_obj_2.second
+    # Return result from comparing via comput_scalar_time
+    return compute_scalar_time(time_obj_1) < compute_scalar_time(time_obj_2)
+
+
+def increment(time_obj, seconds):
+    ret_time_obj = Time()
+    # Copy data from the time_obj to our ret_time_obj
+    ret_time_obj = copy(time_obj)
+
+    ret_time_obj.second += seconds
+    if ret_time_obj.second >= 60: 
+        added_min, remaining_sec = divmod(ret_time_obj.second, 60)
+        ret_time_obj.second = remaining_sec
+        ret_time_obj.minute += added_min
+    if ret_time_obj.minute >= 60:
+        added_hour, remaining_min = divmod(ret_time_obj.minute, 60)
+        ret_time_obj.minute = remaining_min
+        ret_time_obj.hour += added_hour
+    return ret_time_obj
+
+def main():
+    t1 = Time()
+    t1.hour = 12
+    t1.minute = 59
+    t1.second = 30
+
+    t2 = Time()
+    t2.hour = 11
+    t2.minute = 59
+    t2.second = 30    
+    # Do comparison of two time objects, True if t1 occurs before t1, False otherwise
+    #print is_after(t1, t2)
+
+    print "t1:Before increment"
+    print_time(t1)
+    print 
+    print "Printing pure function increment value"
+    print_time(increment(t1, 600))
+    print
+    print "t1:After increment"
+    print_time(t1)
+
+
+if __name__ == '__main__':
+    main()