Jerry Rocteur wrote:
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On 06/22/2010 01:32 PM, Jerry Rocteur wrote:
My input is NOT CSV, I used this format to try and make the question shorter.
Although I could create a CSV file,
I'd
like to learn how to code a class to work the way I described in the question.
Sorry for misunderstanding. Can you maybe give one example that's not
CSV? Both your demonstrated files actually are CSV like. Can you be more
specific on what actually changes constantly. (Fields given in the
files, or the users in the files, or...)
Can you tell us, why you want to use classes if the dict approach works
great?
As part of learning Python, I'm also learning OOP! That is why I want to know
if this is doable using classes.
The input is not important, I end up with the dictionary as described in the
question and as I asked in the question,
I'd like to access the dictionary as a class and I don't know how or if it is
possible.
Jerry
Dictionary is already a class in python, everything is an object
actually (even class are objects).
A python OOP approach to your problem would be to subclass the builtin
'dict' class and override / add the methods.
Here is an example how you can for your User dictionary to accept only
some types of values.
class User(object):
def __init__(self, user, secnum, name):
self.user = user
self.secnum = secnum
self.name = name
def __str__(self):
return "%(name)s <%(user)s> -- secnum :%(secnum)d" % self.__dict__
def __repr__(self):
return self.__str__()
class Users(dict):
def __init__(self):
dict.__init__(self) # call the baseclass constructor
def __setitem__(self, user, value):
if isinstance(value, User):
dict.__setitem__(self, user, value)
else:
try:
dict.__setitem__(self, user, User(user, value[0], value[1]))
except KeyError:
raise ValueError ("Invalid user format, it shoudl be
either a User object or a tuple (secnum, name)")
users = Users()
users['jro'] = (1325,'john') # the overriden __setitem__ method wil
ltake care of creating the User object for you.
users['dma'] = User('dma', 654968, 'dominic')
for user in users:
print users[user]
# Users objects inherit all dict method, values() for instance
for user in users.values():
print user
For more information: http://docs.python.org/reference/datamodel.html
Read carefully the 3.4.6 section (Emulating container type)
JM
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