On 9/29/2012 11:48 PM, Steven D'Aprano wrote:
On 30/09/12 10:43, Jan Kaliszewski wrote:
Hello,
In http://docs.python.org/release/3.2.3/reference/expressions.html#in we
read: "[...] This can create the illusion of non-transitivity between
supported cross-type comparisons and unsupported comparisons. For
example,
Decimal(2) == 2 and 2 == float(2) but Decimal(2) != float(2)."
[...]
Is it a bug in the docs or in Python itself? (I checked that in 3.2,
but it may be true for 3.3 as well)
Documentation bug. It used to be the case that Decimal and float did not
compare equal:
Questions about past releases are better directed to python-list (where
Steven would have given same answer ;-). But anyway, please open a doc
issue on the tracker to update that item.
steve@runes:~$ python3.1
Python 3.1.3 (r313:86834, Nov 28 2010, 11:28:10)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
py> from decimal import Decimal
py> Decimal(2) == 2.0
False
but starting in 3.2 they do. But of course there are traps for the unwary,
due to binary floats, e.g. Decimal("0.1") != 0.1
--
Terry Jan Reedy
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