On Sat, 25 Mar 2006 21:33:24 -0800, DrConti wrote:
> Dear Python developer community,
> I'm quite new to Python, so perhaps my question is well known and the
> answer too.
>
> I need a variable alias ( what in other languages you would call "a
> pointer" (c) or "a reference" (perl))
Others have given you reasons why you can't do this, or shouldn't do this.
In general, I agree with them -- change your algorithm so you don't
need indirect references.
But if you can't get away from it, here is another work-around that might
help:
> class ObjectClass:
> """ Test primary Key assignment """
>
> if __name__ == "__main__":
>
> ObjectClassInstantiated=ObjectClass()
> ObjectClassInstantiated.AnAttribute='First PK Elem'
> ObjectClassInstantiated.AnotherOne='Second PK Elem'
> ObjectClassInstantiated.Identifier=[]
>
> ObjectClassInstantiated.Identifier.append(ObjectClassInstantiated.AnAttribute)
>
> ObjectClassInstantiated.Identifier.append(ObjectClassInstantiated.AnotherOne)
> print ObjectClassInstantiated.Identifier
> ObjectClassInstantiated.AnAttribute='First PK Elem Changed'
> print ObjectClassInstantiated.Identifier
# helper class
class Indirect:
def __init__(self, value):
self.value = value
def mutate(self, newvalue):
self.value = newvalue
def __eq__(self, other):
return self.value == other
def __repr__(self):
return "-> %r" % self.value
instance = ObjectClass()
instance.attribute = Indirect('First PK Elem')
instance.another_attribute = Indirect('Second PK Elem')
instance.identifier = [instance.attribute, instance.another_attribute]
print instance.identifier
instance.attribute.mutate('First PK Elem Changed')
print instance.identifier
which prints
[-> 'First PK Elem', -> 'Second PK Elem']
[-> 'First PK Elem Changed', -> 'Second PK Elem']
as requested.
--
Steven.
--
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