New submission from Ronald Oussoren:
The following code raises MemoryError instead of creating an empty list:
# START
import sys
class CustomIter:
def __iter__(self):
return self
def __next__(self):
raise StopIteration
def __length_hint__(self):
return sys.maxsize
l = list(CustomIter())
#END
That's because this empty iterator has a __length_hint__ that claims it returns
a very large number of methods.
The function listextend in Objects/listobject.c already ignores
__length_hint__() when using it would overflow the size of the list, it would
IMHO also be better to ignore the length hint when the attempt to resize fails
as __length_hint__() is documented as a hint that may be incorrect.
----------
components: Interpreter Core
messages: 282946
nosy: ronaldoussoren
priority: normal
severity: normal
status: open
title: __length_hint__ isn't a hint for list()
versions: Python 3.5, Python 3.6
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Python tracker <[email protected]>
<http://bugs.python.org/issue28940>
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