str(bytes) in Python 3.0

[Dan Bishop]

On Apr 12, 9:29 am, Carl Banks <pavlovevide... at gmail.com> wrote:
> On Apr 12, 10:06 am, Kay Schluehr <kay.schlu... at gmx.net> wrote:
>
> > On 12 Apr., 14:44, Christian Heimes <li... at cheimes.de> wrote:
>
> > > Gabriel Genellina schrieb:
>
> > > > On the last line, str(x), I would expect 'abc' - same as str(x, 'ascii')
> > > > above. But I get the same as repr(x) - is this on purpose?
>
> > > Yes, it's on purpose but it's a bug in your application to call str() on
> > > a bytes object or to compare bytes and unicode directly. Several months
> > > ago I added a bytes warning option to Python. Start Python as  "python
> > > -bb" and try it again. ;)
>
> > And making an utf-8 encoding default is not possible without writing a
> > new function?
>
> I believe the Zen in effect here is, "In the face of ambiguity, refuse
> the temptation to guess."  How do you know if the bytes are utf-8
> encoded?

True, you can't KNOW that.  Maybe the author of those bytes actually
MEANT to say '¿Cómo estás?' instead of '¿Cómo estás?'.  However,
it's statistically unlikely for a non-UTF-8-encoded string to just
happen to be valid UTF-8.