[Python-Dev] int()'s ValueError behaviour

[M.-A. Lemburg]

Guido van Rossum wrote:
> Go ahead and fix it. This was probably never changed since 1990 or
> so... Do expect some code brakage where people rely on the old
> behavior. :-(
> 
> --Guido
> 
> On 4/9/06, Thomas Wouters <thomas at python.org> wrote:
>> Someone on IRC (who refuses to report bugs on sourceforge, so I guess he
>> wants to remain anonymous) came with this very amusing bug: int(), when
>> raising ValueError, doesn't quote (or repr(), rather) its arguments:
>>
>>  >>> int("")
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in ?
>> ValueError: invalid literal for int():
>>>>> int("34\n\n\n5")
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in ?
>> ValueError: invalid literal for int(): 34
>>
>>
>> 5
>> Unicode behaviour also isn't always consistent:
>>>>> int(u'\u0100')
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in ?
>> UnicodeEncodeError: 'decimal' codec can't encode character u'\u0100' in
>> position 0: invalid decimal Unicode string
>>>>> int(u'\u09ec', 6)
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in ?
>> ValueError: invalid literal for int(): 6
>>
>> And trying to use the 'decimal' codec directly:
>>>>> u'6'.encode('decimal')
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in ?
>> LookupError: unknown encoding: decimal

This part I can explain: the internal decimal codec isn't
made public through the codec registry since it only
supports encoding.

The encoder converts a Unicode decimal strings to plain
ASCII decimals.

The error message looks like a standard codec error message
because the raise_encode_exception() API is used.

>> I'm not sure if the latter problems are fixable, but the former should be
>> fixed by passing the argument to ValueError through repr(), I think. It's
>> also been suggested (by the reporter, and I agree) that the actual base
>> should be in the errormessage too. Is there some reason not to do this that
>> I've overlooked?
>>
>> --
>> Thomas Wouters <thomas at python.org>
>>
>> Hi! I'm a .signature virus! copy me into your .signature file to help me
>> spread!
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>>
> 
> 
> --
> --Guido van Rossum (home page: http://www.python.org/~guido/)
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-- 
Marc-Andre Lemburg
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