[New-bugs-announce] [issue29843] errors raised by ctypes.Array for invalid _length_ attribute

[Oren Milman]

New submission from Oren Milman:

With regard to ctypes.Array:

currently:
>>> from ctypes import *
>>> class T(Array):
...     _type_ = c_int
...     _length_ = -1
...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: array too large
>>> class T(Array):
...     _type_ = c_int
...     _length_ = -1 << 1000
...
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: The '_length_' attribute is too large


Obviously, here the _length_ attribute is too small, not too large.
Thus, the error messages should be changed to be more accurate (optimally, for
any negative _length_, the error message should be the same).

Moreover, in accordance with #29833 (this is a sub-issue of #29833), ValueError
should be raised for any negative _length_ attribute (instead of
OverflowError).


Also, Note that currently, in case _length_ == 0, no error is raised. ISTM that
a ctypes Array of length 0 is useless, so maybe we should raise a ValueError in
this case too?

----------
components: ctypes
messages: 289800
nosy: Oren Milman, serhiy.storchaka
priority: normal
severity: normal
status: open
title: errors raised by ctypes.Array for invalid _length_ attribute
type: behavior
versions: Python 3.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue29843>
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