RetroSearch Browse

Tue May 5 07:19:36 CEST 2009 · https://mail.python.org/pipermail/python-dev/2009-May/089402.html

In Python 2, PyMapping_Check will return 0 for list objects. In Python
3, it returns 1. Obviously, this makes it rather difficult to
differentiate between mappings and other sized iterables. In addition,
it differs from the behavior of the ``collections.Mapping`` ABC --
isinstance([], collections.Mapping) returns False.

I believe the new behavior is erroneous, but would like to confirm
that before filing a bug.

The behavior can be seen from a C extension, or if you're lazy, using ctypes:

Python 2.6.2 (release26-maint, Apr 19 2009, 01:56:41)
[GCC 4.3.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import ctypes
>>> ctypes.CDLL('libpython2.6.so').PyMapping_Check(ctypes.py_object([]))
0

Python 3.0.1+ (r301:69556, Apr 15 2009, 15:59:22)
[GCC 4.3.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import ctypes
>>> ctypes.CDLL('libpython3.0.so').PyMapping_Check(ctypes.py_object([]))
1

Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://mail.python.org/pipermail/python-dev/2009-May/089402.html below:

[Python-Dev] Undocumented change / bug in Python3's PyMapping_Check