Introducing python3 into user system

[Ruslan Makhmatkhanov]

Gerhard Schmidt wrote on 10/17/2016 14:27:
> Am 17.10.2016 um 12:39 schrieb Ruslan Makhmatkhanov:
>> Gerhard Schmidt wrote on 10/17/2016 11:07:
>>> Am 16.10.2016 um 21:22 schrieb Ruslan Makhmatkhanov:
>>>> - if port has a build dependency upon python and it can be built both
>>>> with python2 and python3, force it to build with python3
>>>> - if some standalone application can be running both with python2 and
>>>> python3 and it have equivalent python3 dependencies, force it to be run
>>>> with python3
>>>
>>> What do you mean by "force it"?.
>>
>> I mean set USES=python3.3+ for such ports.
>
> This will install python3.5 on this system regardless if there is a
> working python2.x installation, which is exactly what is wrong. I am a
> software developer who runs legacy systems on python2.7. Forcing ports
> that are able to run with python2.7 to install python3.5 will most
> probably break my systems. USES should always represent the minimum
> requirement not something so feel is something it should use.

I'm not sure how it will break anything if conditions, listed in my 
initial message are complied. Would you please elaborate on that and 
provide an example of such a breakage? python3.5 and python2.7 can 
co-exist. And I just want to remind that we are talking only about 
standalone applications now, with no external dependencies, and also 
about ports that use python only at build phase.

>
> Please do not break systems without a really good reason. This we can
> discus in 4 years when support for python2 will end, but not until than.
>
> Not everyone has the freedom to run only shine new software on shine new
> systems.
>
> Regards
>   Estartu


As far I understand, we should do some preliminary work to make it 
happen. We can't turn 26k of ports to using python3 in one day at 1st of 
January 2020.


-- 
Regards,
Ruslan

T.O.S. Of Reality