[ python-Bugs-1080440 ] float issue for NaN type in .pyc file

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Bugs item #1080440, was opened at 2004-12-07 13:24
Message generated for change (Comment added) made by dileep_nirala
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Category: Python Interpreter Core
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Dileep Nirala (dileep_nirala)
Assigned to: Nobody/Anonymous (nobody)
Summary: float issue for NaN type in .pyc file

Initial Comment:
There is a difference in output between .pyc and .py 
file, while dealing with NaN float. In fact I am doing 
a float range validation as part of my requirement. 

The content of my sample program
[test.py]
aboveMax = 1.8e+308
belowMin = -1.8e+308
print aboveMax, belowMin

While execution:
command: python test.py
output: 1.#INF -1.#INF
This output is expected and good, however if I use 
compiled python file as below,

command: python test.pyc
output: 1.0 -1.0 
This output is wrong, it does not show Nan floating 
point. 


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>Comment By: Dileep Nirala (dileep_nirala)
Date: 2004-12-07 20:54

Message:
Logged In: YES 
user_id=1173293

My test cases passes for the first time but fails second 
times onward since .pyc gets loaded since it's existing.

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Comment By: Tim Peters (tim_one)
Date: 2004-12-07 14:51

Message:
Logged In: YES 
user_id=31435

Python guarantees nothing about behavior in the 
presence of NaNs, infinities, or signed zeroes.  Anything 
you see then is a platform-dependent accident.

This should be closed with a reference to PEP 42 (I don't 
have time to look it all up now -- "non-accidental" IEEE 
behavior is a longstanding feature request, but one 
unlikely to be resolved in the foreseeable future; the 
particular problem here is that the marshal format deals 
in accidental ways with infinities, NaNs, and signed 
zeroes, so accidents in .py files may not be reproduced 
from .pyc files)

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