[ python-Bugs-971106 ] Comparisons of unicode and strings raises UnicodeErrors

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Bugs item #971106, was opened at 2004-06-11 09:07
Message generated for change (Comment added) made by tim_one
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Category: Unicode
Group: Python 2.3
Status: Closed
Resolution: Wont Fix
Priority: 5
Submitted By: Christian Theune (ctheune)
Assigned to: M.-A. Lemburg (lemburg)
Summary: Comparisons of unicode and strings raises UnicodeErrors

Initial Comment:
When comparing unicode and strings the implicit conversion
will raise an exception instead of returning false. See the
example later on.

We (Christian Theune and Jim Fulton) suggest that
if the ordinary string can't be decoded,  that False should
be returned.  This seems to be the only sane approach 
given's Python's policy of implicitly converting strings
to unicode using a default encoding.


Python 2.3.4 (#1, Jun 10 2004, 11:08:42) 
[GCC 3.3.3 20040412 (Gentoo Linux 3.3.3-r6,
ssp-3.3.2-2, pie-8.7.6)] on linux2
Type "help", "copyright", "credits" or "license" for
more information.
>>> class Elephant:
...     pass
... 
>>> e1 = Elephant()
>>> e1 == 5
False
>>> u"asdf" == "asdfö"
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
UnicodeDecodeError: 'ascii' codec can't decode byte
0xf6 in position 4: ordinal not in range(128)
>>> e1 == "asdfö"
False
>>> e1 == u"asdfö"
False
>>> 


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>Comment By: Tim Peters (tim_one)
Date: 2004-06-14 12:48

Message:
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Christian, you and/or Jim would need to make the case on 
Python-Dev to change this behavior, and get Guido to agree.  
The current behavior isn't an accident -- it's functioning as 
documented and designed.  Changing existing behavior isn't 
easy (and shouldn't be easy ...).

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Comment By: M.-A. Lemburg (lemburg)
Date: 2004-06-14 12:21

Message:
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In that case I'll have to close the request as "Won't fix":
comparisons can raise exceptions and if you're comparing
apples and eggs you should get an exception instead of
a misleading result which only hides programming errors.

Sorry.

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Comment By: Christian Theune (ctheune)
Date: 2004-06-14 12:16

Message:
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That's what Jim and I found to be the best solution (for now) 

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Comment By: M.-A. Lemburg (lemburg)
Date: 2004-06-14 12:06

Message:
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I'm not sure what you are suggesting here... do you want
u"asdf" == "asdfö" to return False ?

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