[Python-Dev] PEP 383: Non-decodable Bytes in System Character Interfaces

[R. David Murray]

On Tue, 28 Apr 2009 at 20:29, Glenn Linderman wrote:
> On approximately 4/28/2009 7:40 PM, came the following characters from the 
> keyboard of R. David Murray:
>>  On Tue, 28 Apr 2009 at 13:37, Glenn Linderman wrote:
>> >  C. File on disk with the invalid surrogate code, accessed via the str 
>> >  interface, no decoding happens, matches in memory the file on disk with 
>> >  the byte that translates to the same surrogate, accessed via the bytes 
>> >  interface. Ambiguity.
>>
>>  Unless I'm missing something, one of these is type str, and the other is
>>  type bytes, so no ambiguity.
>
>
> You are missing that the bytes value would get decoded to a str; thus both 
> are str; so ambiguity is possible.

Only if you as the programmer decode it.  Now, I don't understand the
subtleties of Unicode enough to know if Martin has already successfully
addressed this concern in another fashion, but personally I think that
if you as a programmer are comparing funnydecoded-str strings gotten
via a string interface with normal-decoded strings gotten via a bytes
interface, that we could claim that your program has a bug.

--David