[Python-bugs-list] [ python-Bugs-649122 ] marshal/pickle problem with True/False

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Bugs item #649122, was opened at 2002-12-05 19:32
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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=649122&group_id=5470

Category: Python Library
Group: None
>Status: Closed
>Resolution: Invalid
Priority: 5
Submitted By: Shack Toms (shacktoms)
>Assigned to: Michael Hudson (mwh)
Summary: marshal/pickle problem with True/False

Initial Comment:
It appears that True and False are special cases of 
integer 1 and 0 such that...

>>> True is 1
0
>>> False is 0
0

After pickling or marshaling, however, this specialness 
is lost.

>>> pickle.loads(pickle.dumps(True)) is 1
1
>>> pickle.loads(pickle.dumps(True)) is True
0

>>> pickle.loads(pickle.dumps(False)) is 0
1
>>> pickle.loads(pickle.dumps(False)) is False
0

In other words, True is unpickled as a non-special 1 and 
False is unpicked as a non-special 0.

It appears that the problem, the bug, is that neither 
pickle nor marshal distinguishes between True/False 
and 1/0.

>>> pickle.dumps(True) == pickle.dumps(1)
1
>>> pickle.dumps(False) == pickle.dumps(0)
1

>>> pickle.dumps(True) == pickle.dumps(1)
1
>>> pickle.dumps(False) == pickle.dumps(0)
1
>>> marshal.dumps(True) == marshal.dumps(1)
1
>>> marshal.dumps(False) == marshal.dumps(0)
1

My version info...
Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit 
(Intel)] on win32
Microsoft Windows 2000 5.00.2195 Service Pack 3


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>Comment By: Michael Hudson (mwh)
Date: 2002-12-05 19:39

Message:
Logged In: YES 
user_id=6656

I'm afraid you're a bit confused.  In 2.2.x True and False
are integers. They may not actually *be* the integers you
get when you type 1 and 0, but they are still integers.

If you try what you tried in a 2.3a0 build from CVS, you
should see different answers.  Applying identity (`is') to
immutable objects is discouraged for exactly this sort of
reason...

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