Python 3.x doesn't honor sys.tracebacklimit=0

According to 
http://docs.python.org/py3k/library/sys.html#sys.tracebacklimit
when set to 0, it should not print any stack trace, but it does.

Python 3.2 (r32:88445, Feb 20 2011, 21:29:02) [MSC v.1500 32 bit (Intel)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
p3> import sys
p3> sys.tracebacklimit = 0
p3>
p3> def f(x):
...   return f(x-1) if x else 0/0
...
p3> f(5)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in f
  File "<stdin>", line 2, in f
  File "<stdin>", line 2, in f
  File "<stdin>", line 2, in f
  File "<stdin>", line 2, in f
  File "<stdin>", line 2, in f
ZeroDivisionError: division by zero
p3>

Originally reported by Thorsten Kampe in comp.lang.python 2011-5-27
<http://permalink.gmane.org/gmane.comp.python.general/691496>

This was changed a long time ago with 565012d1123d

Is this the intended behavior then? I don't get the rationale for that change.

There is no way to completely supress traceback information now; for sys.tracebacklimit to be of any significance, it must be >= 1; 0 and negative values behave the same as it not being set (that is, a full traceback is printed).

Either code or doc must change (with 'version changed' note). Doc: "The default is 1000. When set to 0 or less, all traceback information is suppressed and only the exception type and value are printed."

Christian's patch: "values <= 0 are replaced with a default value to avoid infinite recursion and other issues." Default is 1000.

I do not see the logic of changing 'nothing' to 'everything'. I am puzzled how printing nothing causes infinite recursion.

This patch fixes the issue. I have also added 2 test cases to make sure it works.

Update patch with better assertions

Do you mind to create a pull request on GitHub Anand?

Issue31949 fixes this and several other bugs in PyTraceBack_Print(), but it may be worth to fix this bug first, especially if the patch contains tests.

messages: + msg305597

assignee: docs@python -> serhiy.storchaka
components: - Documentation

messages: + msg284463

messages: + msg284084
keywords: + patch
nosy: + chillaranand, - docs@python

assignee: docs@python
components: + Documentation