[Python-3000] u'text' as an alias for 'text'?

"Martin v. Löwis" martin at v.loewis.de
Sun Mar 23 22:52:17 CET 2008


Lennart Regebro wrote:
> On Thu, Mar 20, 2008 at 11:02 PM, Mike Meyer <mwm at mired.org> wrote:
>>  Fair enough. But doesn't 2.5->2.6 present the same problem? After all,
>>  you can't start using 2.6 features until everyone is using it, right?
> 
> No, but you can start using 2.6 before everyone is using it, since 2.6
> is backwards compatible with 2.5.

Maybe I'm confusing backwards and forwards compatibility again.

If you add __future__ imports to the 2.6 code, it will stop running
on 2.5. Does that make it "not backwards compatible", or "not forwards
compatible".

> So you write 2.5 code, and run it
> under 2.5 or 2.6. This is not possible with 3.0. You can't write 2.5
> code and run it under 3.0.

Right. You can't do that either if a __future__ import is added to
2.6.

> Yeah, you are right about that point, except for the compilation and
> the fact that you are debugging a different version of the code than
> the one you are writing, which of course is highly confusing, it is
> similar to having 2.5/2.6. The difference is that with 2.5/2.6 you
> develop for one, and then when that works, you make sure it works on
> the other. With 2.6/3.0 you have to develop both at once.

How so? You develop for 2.6, and then make sure it runs on 3.0 -
*exactly* the same as for 2.5/2.6.

Regards,
Martin





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