On Fri, Mar 13, 2020 at 5:16 AM Marco Sulla
<python-id...@marco.sulla.e4ward.com> wrote:
>
> On Thu, 12 Mar 2020 at 19:05, Chris Angelico <ros...@gmail.com> wrote:
> > The action of deleting a *name* is not the same as disposing of an
> > *object*. You can consider "del x" to be very similar to "x = None",
> > except that instead of rebinding to some other object, it unbinds x
> > altogether.
>
> Exactly. But if `x = None` will return the previous value of x, the
> refcount of the object will be not decreased, and Python does not free
> the object memory.
> An example:
>
> (venv) marco@buzz:~/sources$ python
> Python 3.8.2 (tags/v3.8.2-dirty:7b3ab5921f, Mar 1 2020, 16:16:55)
> [GCC 9.2.0] on linux
> Type "help", "copyright", "credits" or "license" for more information.
> >>> from sys import getrefcount
> >>> a = "nfnjgjsbsjbjbsjlbslj"
> >>> getrefcount(a)
> 2
> >>> a
> 'nfnjgjsbsjbjbsjlbslj'
> >>> getrefcount(a)
> 3
I don't understand your point. What you're showing here is that the
name binding 'a' has a reference to that string, and then getrefcount
itself has one (because the value is "in use" by being a parameter),
and then you add another one using the REPL's "_" binding, at which
point there are three references. What has this to do with the
behaviour if something returned a value?
The broad idea of "del x" returning a value isn't inherently
ridiculous. If you consider name bindings to be like a dictionary
(and, in fact, it will often be implemented with one), then "del x" is
very similar to "namespace.pop('x')", which returns the value that
it's just removed. The semantics, in terms of whether an object can be
garbage collected, would be identical. When the interpreter dels a
name, it simply removes one reference.
ChrisA
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