Why has python3 been created as a seperate language where there is still python2.7 ?

[Christian Tismer]

On 27.06.12 13:02, Chris Angelico wrote:
> On Wed, Jun 27, 2012 at 8:25 PM, Christian Tismer <tismer at stackless.com> wrote:
>> I think, for the small importance of the print statement in code, it
>> would have made the transition easier, if python 3 was as flexible
>> as python 2.7, with a symmetric
>>
>> "from __past__ import print_statement" construct.
>>
> For how long? Will Python require, in perpetuity, the code to support
> this? Must the print statement be enhanced when the print function is?
> What about bug fixes? How much dev time is required to enable backward
> compatibility past a boundary across which backward compatibility was
> not promised? And if there's a limit to the duration of this __past__
> directive, when should it be and what should happen after that point?
>
> Much easier to simply say no.

Just as a note:
It is not that I'm lazy or against python3 or anything.
The opposite is true, as I'm a long-term developer and python evangelist.

My argument simply addresses to get as much acceptance of python3
as quickly as possible, and some hard work put into a backward
feature would IMHO have been better for python3.

I would even like much more drastic changes that python3 actually
does, to make the move really worth moving.

What happened was a bit the opposite: huge effort for making a really
useful python 2.7. My strategy would have put less effort into that,
and more to make python3 clearly the thing that people want and need.
Right now I think python 2.7 is simply too good.

-----
And especially for the print statement:

It is a bad idea that the print statement _must_ create a syntax error.
It is IMHO not important to support it really and could just work more
or less, with no new features, because as said:

print, function or not, is not important enough to enforce a rewrite
everywhere because of syntax error. That hides the real semantic
changes which _are_ important.

So what I would have done is to let it work in an imperfect way. People
then have the chance to rewrite with the print function, where it makes
sense. But old packages which need to be changed, only because they
have lots of

     if DEBUG:
         print xxx, yyy, ...

could just stay unchanged or migrated later after the real meat has
been properly tested etc. Well, I missed the right time to discuss that,
so this is just a useless note about history.

cheers -- Chris

-- 
Christian Tismer             :^)   <mailto:tismer at stackless.com>
tismerysoft GmbH             :     Have a break! Take a ride on Python's
Karl-Liebknecht-Str. 121     :    *Starship* http://starship.python.net/
14482 Potsdam                :     PGP key -> http://pgp.uni-mainz.de
work +49 173 24 18 776  mobile +49 173 24 18 776  fax n.a.
PGP 0x57F3BF04       9064 F4E1 D754 C2FF 1619  305B C09C 5A3B 57F3 BF04
       whom do you want to sponsor today?   http://www.stackless.com/