anything like C++ references?
tomas at fancy.org
Tue Jul 15 05:57:44 CEST 2003
Stephen Horne wrote:
> >Are they really technicalities, though? I mean, a mutable object
> >can be changed. It's the same object, just changed. Immutable
> >objects, however, can't be changed. You can get something that
> >appears like changing it, but it's actually building a new thing
> >and binding the label to that new thing.
> Yes. But the thing being changed *is* an object, *not* a value. Values
> are always immutable - basic fact of mathematics.
Sure, but we're not modelling pure mathematics, we're modelling a
level of abstraction that's appropriate for the problem that
class Chameleon: pass
a = Chameleon()
b = a
now, a and b represent the same thing. Say it's a chameleon out
in the woods.
If I say:
then I expect
to return some brown color, since a and b are referring to the
We could argue that "color" should be an immutable object within
the chameleon class, and I think argue quite successfully.
However, the chameleon itself doesn't become a different animal,
it still is the same size and has the same scars.
> Variables in mathematics are bound to values. I think Python
> should be implemented in a way that respects that.
I don't agree, because Python is a language that allows us to
model objects in a way that is comfortable to us. If I wanted to
use a more mathematically pure language, I would, but that
language would likely not be suited to the problems I'm trying to
> To me, 'Pythonic' expresses 'doing the right thing'. In this
> case, in my view, Python does the wrong thing and expects
> everyone to get used to it.
In my view, Python does largely what I want it to do regardless
of mathematical correctness.
There's really no reason to send a copy of your
followup to my email address, so please don't.
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