[issue33323] inconsistent stack trace for exceptions thrown in generators passed to min/max
New submission from Naris R : if a generator passed to min/max throws an exception, the stack trace is normally shown on the line that caused the exception, but if the exception is a StopIteration, the trace only shows the line where the max/min function was called. I was writing a minimax and alphabeta search with generator expression and list comprehension and accidentally passed an empty iterator to the next function while computing states for minimax and it took a very long time to find out where the error was actually caused. -- messages: 315561 nosy: Naris R priority: normal severity: normal status: open title: inconsistent stack trace for exceptions thrown in generators passed to min/max type: behavior versions: Python 2.7, Python 3.6 ___ Python tracker <https://bugs.python.org/issue33323> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue33323] inconsistent stack trace for exceptions thrown in generators passed to min/max
Naris R added the comment:
This is a little bit contrived but it demonstrates the problem.
```
def good_exception():
raise Exception('something bad happened')
def bad_exception():
return next(iter([]))
def good(n):
return good_exception() + n
def bad(n):
return n - bad_exception()
import traceback
try:
max(good(i) for i in range(4)) # desirable behaviour
except:
traceback.print_exc()
try:
min(bad(i) for i in range(7)) # unhelpful error message
except:
traceback.print_exc()
```
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[issue34427] calling MutableSequence.extend on self produces infinite loop
New submission from Naris R :
Example:
```
from typing import MutableSequence, TypeVar
CliffordGate = TypeVar('CliffordGate')
class QCircuit(MutableSequence[CliffordGate]):
def __init__(self, gates):
self.gates = list(gates)
def __repr__(self):
return f'{self.__class__.__name__}({self.gates})'
def __getitem__(self, key):
return self.gates[key]
def __setitem__(self, key, item):
self.gates[key] = item
def __delitem__(self, key):
del self.gates[key]
def insert(self, key, item):
self.gates.insert(key, item)
a = QCircuit(['H0', 'S2'])
a += a
```
--
components: Library (Lib)
messages: 323696
nosy: Naris R
priority: normal
severity: normal
status: open
title: calling MutableSequence.extend on self produces infinite loop
type: behavior
versions: Python 3.7
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[issue34427] calling MutableSequence.extend on self produces infinite loop
Naris R added the comment: I forgot to copy over __len__ in the example -- ___ Python tracker <https://bugs.python.org/issue34427> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue34427] calling MutableSequence.extend on self produces infinite loop
Change by Naris R : -- nosy: +rhettinger, stutzbach ___ Python tracker <https://bugs.python.org/issue34427> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue34427] calling MutableSequence.extend on self produces infinite loop
Change by Naris R : -- keywords: +patch pull_requests: +8291 stage: -> patch review ___ Python tracker <https://bugs.python.org/issue34427> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
