Comments on: Python: di

By: Satoru

Satoru — Sun, 27 Sep 2009 19:01:41 +0000

Hi.
I don’t know Python well. Is it possible to code like this without di?

import di

class Debug:
@classmethod
def show(self, *val_name):
print “”,
print ” “.join([m + ":" + str(di.di(id(eval(m)))) for m in val_name])

if __name__ == ‘__main__’:
total = 0
for n in range(10):
total += n
Debug.show(“n”, “total”)

By: Tiran

Tiran — Wed, 21 Nov 2007 17:18:17 +0000

Here is just a friendly reminder from me. Python has something like di() already build in:

>>> import _ctypes
>>> _ctypes.PyObj_FromPtr(id(_ctypes))

By: bbum’s weblog-o-mat » Blog Archive » TwistedElephant: A Memory Debugger for Twisted Applications

Sat, 15 Sep 2007 17:11:19 +0000

[...] one-off bits of logging within the target application that used Python’s GC module and my di() hack such that I could explore the active object graph within the Twisted [...]

By: bbum’s weblog-o-mat » Blog Archive » Python’s Weakref is weak sauce.

Thu, 13 Sep 2007 05:08:35 +0000

[...] little bit ago, I released an itty bitty Python module called di that caused quite the kerfluffle. di is simply the inverse of id; di(id(someObject)) will simply [...]

By: DeanG

DeanG — Sun, 26 Aug 2007 17:18:05 +0000

Guess we’re not all Consenting Adults here.

A good compromise may be to include it at the same class of feature as Assert: included, but not when run when optimization set at compile time. Would that be too restrictive for the various debugging environments?

By: Peter Fein

Peter Fein — Sun, 26 Aug 2007 15:19:14 +0000

Shalabh: No, my code does not have an id-reuse problem. id() is called from the __init__. There’s no way you could end up with two live objects at the same address at the same time.

By: Shalabh

Shalabh — Sun, 26 Aug 2007 06:23:07 +0000

Ok, I saw the comment about logging an id and finding the object based on the id in the log file, which means the same instance of the interpreter is still running. But you may get a different object back as ids are reused. Peter Fein’s code has the same issue since it uses the id as the key. But it’s a simple enhancement to use (id, count) as they key.

By: Shalabh

Shalabh — Sun, 26 Aug 2007 06:09:48 +0000

Since ids are reused, how can you be sure the object you got from di is the same one you called id() on? In fact this happens easily on my Mac:
>>> o = object() >>> id(o) 5387360 >>> del o >>> o2 = object() >>> id(o2) 5387360 >>>

Also, can you tell us why a weakref didn’t work for you? For example, how did you pass the id of the object from the code where the object existed, to the code where the object needed to be ‘found’?

By: Chris Hanson

Chris Hanson — Sat, 25 Aug 2007 03:30:19 +0000

You should get in touch with Guido and see if something like this could be added to Python 3000 core language. It would be really useful in all sorts of situations!

By: bbum

bbum — Sat, 25 Aug 2007 02:46:03 +0000

Thanks for the code. While a step in the right direction, there would still be a lot of work left to make it do what I was able to do based upon di(). It is about 9 lines of code longer than what I needed.

In the end, my particular problem — stupid huge amounts of memory leaks due to overrooting of objects — has been solved very very quickly with minimal fuss and full cognizance of the limited applicability of the model.

Sometimes a quick, nasty, intrusive, and fragile hack is exactly the right answer.