dictionaries/pointers

[Rob Conner]

I dont know how to do this and can't think of a simple way to.

All I want is a dictionary where two keys point to the same object.
(to steal the ascii art from
http://starship.python.net/crew/mwh/...jectthink.html)
I want sometihng like this:

,------. +-------+
| dict |------>|+-----+| +---+
`------' || "a" |+---->| 1 |
|+-----+| +---+
| | ^
|+-----+| |
|| "b" |+-------'
|+-----+|
+-------+
| |
|+-----+| +---+
|| "c" |+---->| 2 |
|+-----+| +---+
+-------+

Where if I change "a" or "b" to 3 the other one will change?
Is this even possible? How would I do it?

[Erik Max Francis]

Rob Conner wrote:

I dont know how to do this and can't think of a simple way to.

All I want is a dictionary where two keys point to the same object.
(to steal the ascii art from
http://starship.python.net/crew/mwh/...jectthink.html)
I want sometihng like this:

,------. +-------+
| dict |------>|+-----+| +---+
`------' || "a" |+---->| 1 |
|+-----+| +---+
| | ^
|+-----+| |
|| "b" |+-------'
|+-----+|
+-------+
| |
|+-----+| +---+
|| "c" |+---->| 2 |
|+-----+| +---+
+-------+

Where if I change "a" or "b" to 3 the other one will change?
Is this even possible? How would I do it?

Objects of type int are immutable in Python, so you'll need a helper
class to do this. Try something like:

class Container: .... def __init__(self, value=None): self.value = value
.... def get(self): return self.value
.... def set(self, value): self.value = value
.... one = Container(1)
myDictionary = {}
myDictionary['a'] = one
myDictionary['b'] = one
myDictionary['b'].set(3)
print myDictionary['a'].get()

3

--
Erik Max Francis && ma*@alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Never make a promise or plan / Take a little love where you can
-- Florence, _Chess_

[Dave Hansen]

On 7 Oct 2005 14:23:49 -0700, "Rob Conner" <rt******@gmail.com> wrote:

I dont know how to do this and can't think of a simple way to.

All I want is a dictionary where two keys point to the same object.
(to steal the ascii art from
http://starship.python.net/crew/mwh/...jectthink.html)
I want sometihng like this:

,------. +-------+
| dict |------>|+-----+| +---+
`------' || "a" |+---->| 1 |
|+-----+| +---+
| | ^
|+-----+| |
|| "b" |+-------'
|+-----+|
+-------+
| |
|+-----+| +---+
|| "c" |+---->| 2 |
|+-----+| +---+
+-------+

Where if I change "a" or "b" to 3 the other one will change?
Is this even possible? How would I do it?

A simple, ugly answer: Use a mutable object rather than a plain
integer. Example:

elt = [1]
dict = {"a":elt, "b":elt, "c":[2]}
print dict {'a': [1], 'c': [2], 'b': [1]} dict["a"][0] = 3
print dict {'a': [3], 'c': [2], 'b': [3]}

Regards,

-=Dave
--
Change is inevitable, progress is not.