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| """This module contains a code example related to
Think Python, 2nd Edition
by Allen Downey
http://thinkpython2.com
Copyright 2015 Allen Downey
License: http://creativecommons.org/licenses/by/4.0/
"""
from __future__ import print_function, division
class Time:
"""Represents the time of day.
attributes: hour, minute, second
"""
def __init__(self, hour=0, minute=0, second=0):
"""Initializes a time object.
hour: int
minute: int
second: int or float
"""
self.hour = hour
self.minute = minute
self.second = second
def __str__(self):
"""Returns a string representation of the time."""
return '%.2d:%.2d:%.2d' % (self.hour, self.minute, self.second)
def print_time(self):
"""Prints a string representation of the time."""
print(str(self))
def time_to_int(self):
"""Computes the number of seconds since midnight."""
minutes = self.hour * 60 + self.minute
seconds = minutes * 60 + self.second
return seconds
def is_after(self, other):
"""Returns True if t1 is after t2; false otherwise."""
return self.time_to_int() > other.time_to_int()
def __add__(self, other):
"""Adds two Time objects or a Time object and a number.
other: Time object or number of seconds
"""
if isinstance(other, Time):
return self.add_time(other)
else:
return self.increment(other)
def __radd__(self, other):
"""Adds two Time objects or a Time object and a number."""
return self.__add__(other)
def add_time(self, other):
"""Adds two time objects."""
assert self.is_valid() and other.is_valid()
seconds = self.time_to_int() + other.time_to_int()
return int_to_time(seconds)
def increment(self, seconds):
"""Returns a new Time that is the sum of this time and seconds."""
seconds += self.time_to_int()
return int_to_time(seconds)
def is_valid(self):
"""Checks whether a Time object satisfies the invariants."""
if self.hour < 0 or self.minute < 0 or self.second < 0:
return False
if self.minute >= 60 or self.second >= 60:
return False
return True
def int_to_time(seconds):
"""Makes a new Time object.
seconds: int seconds since midnight.
"""
minutes, second = divmod(seconds, 60)
hour, minute = divmod(minutes, 60)
time = Time(hour, minute, second)
return time
def main():
start = Time(9, 45, 00)
start.print_time()
end = start.increment(1337)
#end = start.increment(1337, 460)
end.print_time()
print('Is end after start?')
print(end.is_after(start))
print('Using __str__')
print(start, end)
start = Time(9, 45)
duration = Time(1, 35)
print(start + duration)
print(start + 1337)
print(1337 + start)
print('Example of polymorphism')
t1 = Time(7, 43)
t2 = Time(7, 41)
t3 = Time(7, 37)
total = sum([t1, t2, t3])
print(total)
if __name__ == '__main__':
main()
|