Modifying the value of a float-like object

Ben Finney ben+python at benfinney.id.au
Wed Apr 15 06:17:40 CEST 2009


Steven D'Aprano <steven at REMOVE.THIS.cybersource.com.au> writes:

> On Tue, 14 Apr 2009 06:03:58 -0700, Eric.Le.Bigot wrote:
> > The goal is to maintain a list [x, y,…] of these float-like
> > objects, and to modify their value on the fly (with something like
> > x.value = 3.14) so that any expression like "x
> > +y" uses the new value.
> 
> Why is that the goal? If you want to change the value of x, just
> change the value of x.

As you're aware (but Eric may not be), Python doesn't have “change the
value of x”. The closest would be to re-bind the name ‘x’ to a different
value, which would not be what Eric is asking for.

If I understand correctly, Eric wants something with the following
behaviour:

    >>> foo = [floatref(3.14), floatref(1.41)]
    >>> bar = foo[0]
    >>> baz = foo[1]
    >>> foo
    [3.14, 1.41]
    >>> (bar, baz)
    (3.14, 1.41)

    >>> foo[1].changevalue(1.62)
    >>> foo
    [3.14, 1.62]
    >>> (bar, baz)
    (3.14, 1.62)

and is asking how to get such a ‘floatref’.

-- 
 \        “If you go parachuting, and your parachute doesn't open, and |
  `\        you friends are all watching you fall, I think a funny gag |
_o__)             would be to pretend you were swimming.” —Jack Handey |
Ben Finney



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