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Created page with "Category:rchanCategory:OPS435-Python OPS435 Python Lab 7 OBJECTIVES (1) Create functions to process programmer-defined type objects. (2) Binding functions into metho..."
[[Category:rchan]][[Category:OPS435-Python]]
OPS435 Python Lab 7
OBJECTIVES
(1) Create functions to process programmer-defined type objects.
(2) Binding functions into methods for programmer-defined type objects.
Overview:
Object-oriented programming is conceptually one level higher than simply structured programming style as you've experienced in Bash or C. In this lab, we're going to look at a few object-oriented programming examples using the Python language.
Reference:
Time object from '''Think Python''' Chapter 16 and 17
Date object from '''OPS435 Assignment 1'''
=Investigation 1: Objects and Functions=
== Part 1 - Simple Object Class with external functions ==
In this part, we consider a time object which has three data attributes, namely: hour, minute, and second. The following Python script '''lab7a.py''' provides the blue print for building such a time object and also define three external functions that can manipulate the time object.
<source lang="python">
#!/usr/bin/env python3
class Time:
"""Simple object type for time of the day.
data attributes: hour, minute, second
"""
def __init__(self,hour=12,minute=0,second=0):
"""constructor for time object"""
self.hour = hour
self.minute = minute
self.second = second
def format_time(t):
"""Return time object (t) as a formatted string"""
return '%.2d:%.2d:%.2d' % (t.hour, t.minute, t.second)
def sum_times(t1, t2):
"""Add two time objests and return the sum."""
sum = Time(0,0,0)
sum.hour = t1.hour + t2.hour
sum.minute = t1.minute + t2.minute
sum.second = t1.second + t2.second
return sum
def valid_time(t):
"""check for the validity of the time object attributes:
24 > hour > 0
60 > minute > 0
60 > second > 0 """
if t.hour < 0 or t.minute < 0 or t.second < 0:
return False
if t.minute >= 60 or t.second >= 60 or t.hour >= 24:
return False
return True
</source>
:'''Perform the following steps:'''
:# Download or create the above Pythone script '''lab7a.py''' in your ~/ops435/lab7 directory.
:# Create a new Python script named '''lab7a1.py''' in the lab7 directory:
<source lang="bash">
cd ~/ops435/lab7
vi ~/ops435/lab7/lab7a1.py
</source>
:# Place the following content inside the new python file '''lab7a1.py''' and save it:<source lang="python">
#!/usr/bin/env python3
# Student ID: [seneca_id]
from lab7a import *
t1 = Time(8,0,0)
t2 = Time(8,55,0)
t3 = Time(9,50,0)
td = Time(0,50,0)
tsum1 = sum_times(t1,td)
tsum2 = sum_times(t2,td)
tsum3 = sum_times(t3,td)
ft = format_time
print(ft(t1),'+',ft(td),'-->',ft(tsum1))
print(ft(t2),'+',ft(td),'-->',ft(tsum2))
print(ft(t3),'+',ft(td),'-->',ft(tsum3))
</source>
OPS435 Python Lab 7
OBJECTIVES
(1) Create functions to process programmer-defined type objects.
(2) Binding functions into methods for programmer-defined type objects.
Overview:
Object-oriented programming is conceptually one level higher than simply structured programming style as you've experienced in Bash or C. In this lab, we're going to look at a few object-oriented programming examples using the Python language.
Reference:
Time object from '''Think Python''' Chapter 16 and 17
Date object from '''OPS435 Assignment 1'''
=Investigation 1: Objects and Functions=
== Part 1 - Simple Object Class with external functions ==
In this part, we consider a time object which has three data attributes, namely: hour, minute, and second. The following Python script '''lab7a.py''' provides the blue print for building such a time object and also define three external functions that can manipulate the time object.
<source lang="python">
#!/usr/bin/env python3
class Time:
"""Simple object type for time of the day.
data attributes: hour, minute, second
"""
def __init__(self,hour=12,minute=0,second=0):
"""constructor for time object"""
self.hour = hour
self.minute = minute
self.second = second
def format_time(t):
"""Return time object (t) as a formatted string"""
return '%.2d:%.2d:%.2d' % (t.hour, t.minute, t.second)
def sum_times(t1, t2):
"""Add two time objests and return the sum."""
sum = Time(0,0,0)
sum.hour = t1.hour + t2.hour
sum.minute = t1.minute + t2.minute
sum.second = t1.second + t2.second
return sum
def valid_time(t):
"""check for the validity of the time object attributes:
24 > hour > 0
60 > minute > 0
60 > second > 0 """
if t.hour < 0 or t.minute < 0 or t.second < 0:
return False
if t.minute >= 60 or t.second >= 60 or t.hour >= 24:
return False
return True
</source>
:'''Perform the following steps:'''
:# Download or create the above Pythone script '''lab7a.py''' in your ~/ops435/lab7 directory.
:# Create a new Python script named '''lab7a1.py''' in the lab7 directory:
<source lang="bash">
cd ~/ops435/lab7
vi ~/ops435/lab7/lab7a1.py
</source>
:# Place the following content inside the new python file '''lab7a1.py''' and save it:<source lang="python">
#!/usr/bin/env python3
# Student ID: [seneca_id]
from lab7a import *
t1 = Time(8,0,0)
t2 = Time(8,55,0)
t3 = Time(9,50,0)
td = Time(0,50,0)
tsum1 = sum_times(t1,td)
tsum2 = sum_times(t2,td)
tsum3 = sum_times(t3,td)
ft = format_time
print(ft(t1),'+',ft(td),'-->',ft(tsum1))
print(ft(t2),'+',ft(td),'-->',ft(tsum2))
print(ft(t3),'+',ft(td),'-->',ft(tsum3))
</source>