I'm new to programming and have an assignment I've been working at for awhile. I understand defining functions and a lot of the basics but I'm kind of running into a brick wall at this point.
I'm trying to figure this one out and don't really understand how the 'class' feature works yet. I'd appreciate any help with this one; also any help with some python resources that have can dummy down how/why classes are used.
You've been going to work on a database project at work for sometime now. Your boss encourages you to program the database in Python. You disagree, arguing that Python is not a database language but your boss persists by providing the source code below for a sample telephone database.
He asks you to do two things:
Evaluate the existing source code and extend it to make it useful for managers in the firm. (You do not need a GUI interface, just work on the database aspects: data entry and retrieval - of course you must get the program to run or properly work
He wants you to critically evaluate Python as a database tool.
Import the sample code below into the Python IDLE and enhance it, run it and debug it. Add features to make this a more realistic database tool by providing for easy data entry and retrieval.
import shelve
import string
UNKNOWN = 0
HOME = 1
WORK = 2
FAX = 3
CELL = 4
class phoneentry:
def __init__(self, name = 'Unknown', number = 'Unknown',
type = UNKNOWN):
self.name = name
self.number = number
self.type = type
# create string representation
def __repr__(self):
return('%s:%d' % ( self.name, self.type ))
# fuzzy compare or two items
def __cmp__(self, that):
this = string.lower(str(self))
that = string.lower(that)
if string.find(this, that) >= 0:
return(0)
return(cmp(this, that))
def showtype(self):
if self.type == UNKNOWN: return('Unknown')
if self.type == HOME: return('Home')
if self.type == WORK: return('Work')
if self.type == FAX: return('Fax')
if self.type == CELL: return('Cellular')
class phonedb:
def __init__(self, dbname = 'phonedata'):
self.dbname = dbname;
self.shelve = shelve.open(self.dbname);
def __del__(self):
self.shelve.close()
self.shelve = None
def add(self, name, number, type = HOME):
e = phoneentry(name, number, type)
self.shelve[str(e)] = e
def lookup(self, string):
list = []
for key in self.shelve.keys():
e = self.shelve[key]
if cmp(e, string) == 0:
list.append(e)
return(list)
# if not being loaded as a module, run a small test
if __name__ == '__main__':
foo = phonedb()
foo.add('Sean Reifschneider', '970-555-1111', HOME)
foo.add('Sean Reifschneider', '970-555-2222', CELL)
foo.add('Evelyn Mitchell', '970-555-1111', HOME)
print 'First lookup:'
for entry in foo.lookup('reifsch'):
print '%-40s %s (%s)' % ( entry.name, entry.number, entry.showtype() )
print
print 'Second lookup:'
for entry in foo.lookup('e'):
print '%-40s %s (%s)' % ( entry.name, entry.number, entry.showtype() )
I'm not sure if I'm on the right track but here is what I have so far:
def openPB():
foo = phonedb()
print 'Please select an option:'
print '1 - Lookup'
print '2 - Add'
print '3 - Delete'
print '4 - Quit'
entry=int(raw_input('>> '))
if entry==1:
namelookup=raw_input('Please enter a name: ')
for entry in foo.lookup(namelookup):
print '%-40s %s (%s)' % (entry.name, entry.number, entry.showtype() )
elif entry==2:
name=raw_input('Name: ')
number=raw_input('Number: ')
showtype=input('Type (UNKNOWN, HOME, WORK, FAX, CELL): \n>> ')
for entry in foo.add(name, number, showtype): #Trying to figure out this part
print '%-40s %s (%s)'% (entry.name, entry.number, entry.showtype() )
elif entry==3:
delname=raw_input('Please enter a name to delete: ')
# #Trying to figure out this part
print "Contact '%s' has been deleted" (delname)
elif entry==4:
print "Phone book is now closed"
quit
else:
print "Your entry was not recognized."
openPB()
openPB()
