Accessing value stack
Hi, is it possible to access the values stored on the stack in Python stack machine from Python? As in, consider expression: tmp = foo() + bar() At the point in time when bar() is called, foo() already returned something, and that value is on top of the stack in that frame, a few steps after bar() returns, that value is added to bar and is lost. I would very much like to be able to read (and maybe even change) that ephemeral value. If it is absolutely not possible to achieve from Pythonland, I welcome pointers on how to write a C/cython/types extension to achieve this. Thanks, d.
Hello. We are sorry but we cannot help you. This mailing list is to work on developing Python (adding new features to Python itself and fixing bugs); if you're having problems learning, understanding or using Python, please find another forum. Probably python-list/comp.lang.python mailing list/news group is the best place; there are Python developers who participate in it; you may get a faster, and probably more complete, answer there. See http://www.python.org/community/ for other lists/news groups/fora. Thank you for understanding. On Mon, Jan 07, 2013 at 03:06:51PM +0100, Dima Tisnek <dimaqq@gmail.com> wrote:
Hi, is it possible to access the values stored on the stack in Python stack machine from Python?
In short: it's possible but very much discouraged. Don't hack into python internals. Oleg. -- Oleg Broytman http://phdru.name/ phd@phdru.name Programmers don't die, they just GOSUB without RETURN.
On Mon, Jan 7, 2013 at 4:22 PM, Oleg Broytman <phd@phdru.name> wrote:
Hello.
We are sorry but we cannot help you. This mailing list is to work on developing Python (adding new features to Python itself and fixing bugs); if you're having problems learning, understanding or using Python, please find another forum. Probably python-list/comp.lang.python mailing list/news group is the best place; there are Python developers who participate in it; you may get a faster, and probably more complete, answer there. See http://www.python.org/community/ for other lists/news groups/fora. Thank you for understanding.
On Mon, Jan 07, 2013 at 03:06:51PM +0100, Dima Tisnek <dimaqq@gmail.com> wrote:
Hi, is it possible to access the values stored on the stack in Python stack machine from Python?
In short: it's possible but very much discouraged. Don't hack into python internals.
Is it possible? I claim it's not (from *Python* because obviously data is in memory). Cheers, fijal
On Mon, Jan 7, 2013 at 10:46 AM, Maciej Fijalkowski <fijall@gmail.com> wrote:
On Mon, Jan 7, 2013 at 4:22 PM, Oleg Broytman <phd@phdru.name> wrote:
Hello.
We are sorry but we cannot help you. This mailing list is to work on developing Python (adding new features to Python itself and fixing bugs); if you're having problems learning, understanding or using Python, please find another forum. Probably python-list/comp.lang.python mailing list/news group is the best place; there are Python developers who participate in it; you may get a faster, and probably more complete, answer there. See http://www.python.org/community/ for other lists/news groups/fora. Thank you for understanding.
On Mon, Jan 07, 2013 at 03:06:51PM +0100, Dima Tisnek <dimaqq@gmail.com> wrote:
Hi, is it possible to access the values stored on the stack in Python stack machine from Python?
In short: it's possible but very much discouraged. Don't hack into python internals.
Is it possible? I claim it's not (from *Python* because obviously data is in memory).
Nope, it's not.
On Mon, Jan 7, 2013 at 11:32 AM, Brett Cannon <brett@python.org> wrote:
On Mon, Jan 7, 2013 at 10:46 AM, Maciej Fijalkowski <fijall@gmail.com> wrote:
On Mon, Jan 7, 2013 at 4:22 PM, Oleg Broytman <phd@phdru.name> wrote:
On Mon, Jan 07, 2013 at 03:06:51PM +0100, Dima Tisnek <dimaqq@gmail.com> wrote:
Hi, is it possible to access the values stored on the stack in Python stack machine from Python?
In short: it's possible but very much discouraged. Don't hack into python internals.
Is it possible? I claim it's not (from *Python* because obviously data is in memory).
Nope, it's not.
I took that as a challenge, and just tried to do it using gc.get_referents(). ;-) Didn't work though... which actually makes me wonder if that's a bug in gc.get_referents(), or whether I'm making a bad assumption about when you'd have to run gc.get_referents() on a frame in order to see items from the value stack included. Could this actually be a bug in frames' GC implementation, or are value stack items not supposed to count for GC purposes?
On Mon, Jan 7, 2013 at 10:40 PM, PJ Eby <pje@telecommunity.com> wrote:
On Mon, Jan 7, 2013 at 11:32 AM, Brett Cannon <brett@python.org> wrote:
On Mon, Jan 7, 2013 at 10:46 AM, Maciej Fijalkowski <fijall@gmail.com> wrote:
On Mon, Jan 7, 2013 at 4:22 PM, Oleg Broytman <phd@phdru.name> wrote:
On Mon, Jan 07, 2013 at 03:06:51PM +0100, Dima Tisnek <dimaqq@gmail.com> wrote:
Hi, is it possible to access the values stored on the stack in Python stack machine from Python?
In short: it's possible but very much discouraged. Don't hack into python internals.
Is it possible? I claim it's not (from *Python* because obviously data is in memory).
Nope, it's not.
I took that as a challenge, and just tried to do it using gc.get_referents(). ;-)
Didn't work though... which actually makes me wonder if that's a bug in gc.get_referents(), or whether I'm making a bad assumption about when you'd have to run gc.get_referents() on a frame in order to see items from the value stack included. Could this actually be a bug in frames' GC implementation, or are value stack items not supposed to count for GC purposes?
valustack is a static list in C (it's not a Python list at all) that's stored on the frame. You can't do it that way. gc.get_referrers returns you only python objects (and in fact should return you only python objects that are accessible otherwise, but those details are really implementation-dependent)
participants (5)
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Brett Cannon -
Dima Tisnek -
Maciej Fijalkowski -
Oleg Broytman -
PJ Eby