[Python-Dev] Python and the Unicode Character Database

[Michael Foord]

On 28/11/2010 23:33, "Martin v. Löwis" wrote:
>>>>>>>> float('١٢٣٤.٥٦')
>>>>> 1234.56
>> Even if this is somehow an accident or something that someone snuck in,
>> I think it a good idea that *users* be able to input amounts with their
>> native digits. That is different from requiring *programmers* to write
>> literals with euro-ascii-digits
> So one question is what kind of data float() is aimed at. I claim that
> it is about "programmer" data, not "user" data. If it supported "user"
> data, it probably would have to support "1,000" to denote 1e3 in the
> U.S., and denote 1e0 in Germany. Our users are generally confused
> on whether they should use th full stop or the comma as the decimal
> separator.
>
FWIW the C# equivalent is locale aware *unless* you pass in a specific 
culture.
(System.Double.Parse):

http://msdn.microsoft.com/en-us/library/fd84bdyt.aspx

If you're not aware that your code may be run on non-US computers this 
is a trap for the unwary. If you *are* aware then it is very useful.

An alternative overload allows you to specify the culture used to do the 
conversion:

http://msdn.microsoft.com/en-us/library/t9ebt447.aspx

Michael

> As not even the locale-dependent issues are considered in float(),
> it is clear to me that entering local numbers cannot possibly be
> the objective of the function.
>
> Instead, following a wide-spread Python convention, it is meant to be
> the reverse of repr().
>
> Can you name a single person who actually wants to write '١٢٣٤.٥٦'
> as a number? I'm fairly skeptical that users of arabic-indic digits.
> Instead,
>
> http://en.wikipedia.org/wiki/Decimal_separator
>
> suggests that they would rather U+066B, i.e. '١٢٣٤٫٥٦', which isn't
> supported by Python.
>
> Regards,
> Martin
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