Part B: Class Time

You will develop a new data type to model the time on a 24 hour clock, where the three data members represent the hour, the minutes and the seconds. Use the date.py module as a guide.

It will be named class Time, and each object of that type will have three instance variables (__hour, _mins and _secs). The module will be named clock.py.

5. Develop the function member named _str_ which will be used to display a human-readable representation of an object of type Time in Python programs:

a. Return a string with the format hh:mm:ss.

b. Be sure to place leading zeroes in the string for the hour, minutes and seconds.

c. Add a doc string to the constructor documenting the purpose of the function.

6. Save the file containing your class as clock.py, then experiment with your module in the iPython shell:

>>> import clock

>>> A = clock.Time()

>>> print( A )

>>> B = clock.Time(7,12,3)

>>> print( B )

9. We provide the Python program named clockDemo.py that demonstrates the use of your class Time. Test your class using clockDemo.py.

10. Create a new file named lab11b.py which contains the source code from the files named

clock.py and clockDemo.py. That is, create a file which contains both the definition of class Time and the demonstration program. The class definition should be at the top of the file. To create that stand alone file you will need to remove (or comment out) the import clock line (you dont need to import it because it is already in the file). Also, since you have not imported clock you need to change clock.Time to Time. Test that your file is working before submitting.

The date.py file

###########################################################################

## Class Date

###########################################################################

class Date( object ):

__name = [ "Invalid", "January", "February", "March", "April",

"May", "June", "July", "August", "September", "October",

"November", "December" ]

__days = [ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ]

def __init__( self, month=0, day=0, year=0 ):

""" Construct a Date using three integers. """

self.__month = month

self.__day = day

self.__year = year

self.__valid = self.__validate()

def __repr__( self ):

""" Return a string as the formal representation a Date. """

out_str = "Class Date: {:02d}/{:02d}/{:04d}" \

.format( self.__month, self.__day, self.__year )

return out_str

def __str__( self ):

""" Return a string (mm/dd/yyyy) to represent a Date. """

out_str = "{:02d}/{:02d}/{:04d}" \

.format( self.__month, self.__day, self.__year )

return out_str

def __validate( self ):

# Check the month, day and year for validity

# (does not account for leap years)

flag = False

if (1 <= self.__month <= 12) and \

(1 <= self.__day <= Date.__days[self.__month] ) and \

(0 <= self.__year):

flag = True

return flag

def is_valid( self ):

""" Return Boolean flag (valid date?) """

return self.__valid

def from_iso( self, iso_str ):

""" Convert a string (yyyy-mm-dd) into a Date. """

year, month, day = [ int( n ) for n in iso_str.split( '-' )]

self.__month = month

self.__day = day

self.__year = year

self.__valid = self.__validate()

def from_mdy( self, mdy_str ):

""" Convert a string (Mmmmm dd, yyyy) into a Date. """

mdy_list = mdy_str.replace(",","").split()

self.__month = Date.__name.index( mdy_list[0] )

self.__day = int( mdy_list[1].strip() )

self.__year = int( mdy_list[2].strip() )

self.__valid = self.__validate()

def to_iso( self ):

""" Return a string (yyyy-mm-dd) to represent a Date. """

iso_str = "{:04d}-{:02d}-{:02d}" \

.format( self.__year, self.__month, self.__day )

return iso_str

def to_mdy( self ):

""" Return a string (Mmmmm dd, yyyy) to represent a Date. """

mdy_str = "{:s} {:d}, {:04d}" \

.format( Date.__name[self.__month], self.__day, self.__year )

return mdy_str

clockDemo.pyfile

import clock

A = clock.Time( 12, 25, 30 )

print( A )

print( repr( A ) )

print( str( A ) )

print()

B = clock.Time( 2, 25, 3 )

print( B )

print( repr( B ) )

print( str( B ) )

print()

C = clock.Time( 2, 25 )

print( C )

print( repr( C ) )

print( str( C ) )

print()

D = clock.Time()

print( D )

print( repr( D ) )

print( str( D ) )

print()

D.from_str( "03:09:19" )

print( D )

print( repr( D ) )

print( str( D ) )