Is there Python code for accessing an object's reference count?
And does it matter to Python what this count is, other than whether
it is zero or greater than zero (for garbage collection)?
Thanks,
**** Moores
Tutor maillist - Tutor (AT) python (DOT) org

10/3/06, **** Moores <rdm (AT) rcblue (DOT) comwrote:
Is there Python code for accessing an object's reference count?

See sys.getrefcount.

A Roberge

And does it matter to Python what this count is, other than whether
it is zero or greater than zero (for garbage collection)?

Thanks,

**** Moores

Tutor maillist - Tutor (AT) python (DOT) org

Tutor maillist - Tutor (AT) python (DOT) org

At 03:25 AM 10/3/2006, Andre Roberge wrote:
10/3/06, **** Moores <rdm (AT) rcblue (DOT) comwrote:
Is there Python code for accessing an object's reference count?
>
>See sys.getrefcount.

Fascinating. And surprising.
from sys import getrefcount
getrefcount(1)
493
getrefcount(2)
157
getrefcount(3)
60
getrefcount(22)
12
getrefcount(222)
3
getrefcount(222234523452345345)
2
getrefcount(2.23452345345)
2

That refcount for 1 (and 2, 3, and 12) is puzzling to me. I closed
python, called python, and tried it again. Essentially no change.
When would this go to zero? when I shut off my computer?

I just answered that last question by shutting off my computer, and found
from sys import getrefcount
getrefcount(1)
493
q = 1
getrefcount(1)
499
w = 1
getrefcount(1)
500
del w
getrefcount(1)
499
q = 2
getrefcount(1)
498

Still 493. Why?

Then after "q = 1", 499, not 494. Why?

The other refcounts, after w=1, del w, and q=2, are as I expected.

Thanks,

****

Tutor maillist - Tutor (AT) python (DOT) org

**** Moores wrote:
At 03:25 AM 10/3/2006, Andre Roberge wrote:
>10/3/06, **** Moores <rdm (AT) rcblue (DOT) comwrote:
Is there Python code for accessing an object's reference count?
>See sys.getrefcount.

Fascinating. And surprising.
from sys import getrefcount
getrefcount(1)
493
getrefcount(2)
157
getrefcount(3)
60
getrefcount(22)
12
getrefcount(222)
3
getrefcount(222234523452345345)
2
getrefcount(2.23452345345)
2

That refcount for 1 (and 2, 3, and 12) is puzzling to me. I closed
python, called python, and tried it again. Essentially no change.
When would this go to zero? when I shut off my computer?

When you exit Python.

There are quite a few modules loaded automatically when Python starts
up. It's not too surprising that a few of them reference 1. For example,
defining a function that uses a constant creates a reference to the
constant:
In [2]: sys.getrefcount(100)
[2]: 43

In [3]: def foo():
: return 100
:

In [4]: sys.getrefcount(100)
[4]: 44

Kent

Tutor maillist - Tutor (AT) python (DOT) org

At 04:44 AM 10/3/2006, Kent Johnson wrote:
>**** Moores wrote:
At 03:25 AM 10/3/2006, Andre Roberge wrote:
>10/3/06, **** Moores <rdm (AT) rcblue (DOT) comwrote:
Is there Python code for accessing an object's reference count?
>See sys.getrefcount.
>
Fascinating. And surprising.
from sys import getrefcount
getrefcount(1)
493
getrefcount(2)
157
getrefcount(3)
60
getrefcount(22)
12
getrefcount(222)
3
getrefcount(222234523452345345)
2
getrefcount(2.23452345345)
2

That refcount for 1 (and 2, 3, and 12) is puzzling to me. I closed
python, called python, and tried it again. Essentially no change.
When would this go to zero? when I shut off my computer?
>
>When you exit Python.
>
>There are quite a few modules loaded automatically when Python starts
>up. It's not too surprising that a few of them reference 1. For example,
>defining a function that uses a constant creates a reference to the
>constant:
>In [2]: sys.getrefcount(100)
>[2]: 43
>
>In [3]: def foo():
: return 100
:
>
>In [4]: sys.getrefcount(100)
>[4]: 44

Ah, got it. Thanks again, Kent.

****

Tutor maillist - Tutor (AT) python (DOT) org

Ilias Lazaridis wrote:
how to you get this output format of the shell?
In [2]:
[2]:
IPython
http://ipython.scipy.org/
Kent
Tutor maillist - Tutor (AT) python (DOT) org