Inconsistency producing constant for float "infinity"

[Peter Hansen]

Sybren Stuvel wrote:
> Peter Hansen enlightened us with:
> 
>>I'm investigating a puzzling problem involving an attempt to
>>generate a constant containing an (IEEE 754) "infinity" value.  (I
>>understand that special float values are a "platform-dependent
>>accident" etc...)
> 
> Why aren't you simply using the fpconst package?

Probably because it's not in the stdlib yet, assuming that's still true.

(Using it might be an option anyway.  I'm investigating a problem on 
Win32 with simplejson, so it would be Bob Ippolito's choice whether 
fpconst is a reasonable solution to the problem.)

My guess about marshal was correct.  The problem (value becoming 1.0) 
appears when running from .pyc files.  Immediately after the source code 
is changed, the code works, since it doesn't unmarshal the .pyc file but 
just works from the bytecode freshly compiled in memory.

This demonstrates what would be the heart of the problem, which I guess 
means this is not surprising to almost anyone, but perhaps will be a 
wakeup call to anyone who might still be unaware and has code that 
relies on constants like 1e6666 producing infinities:

 >>> import marshal
 >>> marshal.dumps(1e666)
'f\x061.#INF'
 >>> marshal.loads(marshal.dumps(1e666))
1.0

-Peter