instance creation
Paul MG
paulmg at digitalbrain.com
Tue Sep 24 04:52:20 EDT 2002
Hi
I am dabbling with Python and have run into a bit of an oddness. I
have a class Appointment, with fields Title and Details. I want to
allow two means of construction:
1) Providing Title and Details strings explicitly, to create a new
instance.
2) Providing an ID, which causes that Appointment to be loaded from a
backing store.
Now in C++ or smalltalk, I would do one of
- Provide two constructors:
def __init__(self, name, details):
self.name = name
self.details = details
def __init__(self, id):
load(id)
def load(self, id):
i = open("appointment"+str(id))
self = pickle.load(i)
- Provide a class method (creation method) to instantiate:
def create(id):
i = open("appointment"+str(id))
return pickle.load(i)
However, much of this seems not to work.
- Having two constructors seems to be illegal - or at least the second
overwrites the first.
- Assigning to 'self' in the load method seems to really not work!
- Putting the create() method outside of the class works fine - but I
want it to be a class method on Appointment, goddammit!:) Is there no
way to do this?
Any help would be appreciated, basically i am looking for the python
idiom to do this, as my C++ and Smalltalk idiom's clearly aren't in
the grain of the language!
Thanks very much
Paul MG
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