[ python-Bugs-1729014 ] 0.0 and -0.0 end up referring to the same object

[SourceForge.net]

Bugs item #1729014, was opened at 2007-05-31 15:27
Message generated for change (Tracker Item Submitted) made by Item Submitter
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1729014&group_id=5470

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: Python Interpreter Core
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Johnnyg (swfiua)
Assigned to: Nobody/Anonymous (nobody)
Summary: 0.0 and -0.0 end up referring to the same object

Initial Comment:
I am not really sure whether this is a bug or a feature.

The attached code attempts to demonstrate the problem.

I had some code that was trying to change -0.0 to 0.0 so that the accountants I work with don't panic.

The code was something like this:

if n == -0.0:
    n = 0.0

Regardless of whether n is -0.0 or 0.0 the test passes (which is good).

However after the assignment n is actually -0.0

It looks like python is creating a single object for both -0.0 and 0.0.

Whichever appears first within the local scope seems to be the value that actually gets stored.

Eg changing the code to 

if n == 0.0:
    n = 0.0

gets me the behaviour I wanted.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1729014&group_id=5470