Finding the instance reference of an object

Aaron Brady castironpi at gmail.com
Sat Nov 8 21:44:48 CET 2008


On Nov 8, 1:08 am, Steven D'Aprano <st... at REMOVE-THIS-
cybersource.com.au> wrote:
> On Sat, 08 Nov 2008 18:31:47 +1300, greg wrote:

<Quote in favor of Steven snip>

<Example in favor of Steven snip>

> There's no "obviously" about it. To anyone who has learned that "call-by-
> value" means that a copy is made, "obviously" it does mean copying the
> value. If you have learned a different meaning, then you will believe
> differently.

I don't think it's obvious to everyone what a copy constructor is and
when it's called.  That's ok, it's something you can learn.  I think
Joe's idea is that you can think of every variable in Python as a
pointer, and that clears up some confusions about its variable model.
What happens when a pointer is copied?  What is an example of copying
a pointer in spoken language?

>>> a= [ 1, 2, 3 ]

Are the following true?

The value of 'a' is an object.
The value of that object is [ 1, 2, 3 ].
The value of 'a' is [ 1, 2, 3 ].

If so, 'value' is ambiguous and therefore not very useful as a term.



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