Mailing List Archive

210125 Micha? Górny wrote:
> Changed eselect-python dep removal date to July 2021.
> Not sure if there's a reason to display it to stable users today,
> or delay until the stable request is actually filed.

I've been using Gentoo since 2003 , happily enough most of the time ;
I'm an ordinary desktop user without any special requirements.
Python versions have been one of the reasons for the exceptions.
I finally managed to remove 2.7 from my system yesterday.

I do appreciate your work in this area,
but I can make no sense of the news item below.

> Title: Python preference to follow PYTHON_TARGETS
> Author: Micha? Górny <mgorny@gentoo.org>
> Posted: 2021-01-24
> Revision: 1
> News-Item-Format: 2.0
>
> On 2021-02-01 stable users will switch to a new method of updating
> the preferred Python versions that employs the configuration update
> mechanism in order to follow PYTHON_TARGETS.

What are "preferred Python versions" ? Why are they multiple, not one ?
What is the "configuration update mechanism",
how does it "follow PYTHON_TARGETS" & why are they both needed ?

> We will also deprecate app-eselect/eselect-python,
> and it will stop being installed by default after 2021-07-01.

Why has there been this 3rd method of managing Python versions ?
Why might it still be needed by users ?

> If you wish to use the newest Python version present
> in your PYTHON_TARGETS, you only have to accept configuration changes.

Why doesn't Python behave like most other packages,
ie use the latest installed version ? Why does PYTHON_TARGETS exist ?
Why are the "targets" ? -- it sounds as if they may not be achieved.
What are the "configuration changes" ?
Do you mean those in /etc/python-exec ?

> If you wish to customize the behavior, read on.

I have no wish to customise Python. I don't use it to develop programs ;
it is installed only as a requirement for other packages, eg Portage.
I do use it for a small script to work as a CLI calculator.
Given this, I won't comment on the rest of the news item,
but it makes even less sense to me than the section above.

In /etc/portage/make.conf , I have

USE_PYTHON="2.7 3.5 3.6"
PYTHON_TARGETS="python3_7"
PYTHON_SINGLE_TARGET="python3_7"

'eselect python list' gives

Available Python interpreters, in order of preference:
[1] python3.7
[2] python3.6 (uninstalled)

/etc/python-exec/ contains 1 file 'python-exec.conf',
which says (besides many lines of comment) :

python3.7
python3.6

'eix python' shows

[I] dev-lang/python
Available versions:
(2.7) 2.7.18-r5 ~2.7.18-r6
(3.6) 3.6.12-r1(3.6/3.6m)^t ~3.6.12-r2(3.6/3.6m)^t
(3.7) 3.7.9-r1(3.7/3.7m)^t ~3.7.9-r2(3.7/3.7m)^t
(3.8) 3.8.6-r1^t ~3.8.7-r1^t
(3.9) 3.9.0-r1^t ~3.9.1-r1^t
(3.10) ~3.10.0_alpha3-r1^t ~3.10.0_alpha4^t
{-berkdb bluetooth build examples gdbm hardened ipv6 libressl +ncurses +readline sqlite +ssl test +threads tk verify-sig +wide-unicode wininst +xml ELIBC="uclibc"}
Installed versions: 3.7.9-r1(3.7/3.7m)^t([2021-01-24 23:26:15])(gdbm ncurses readline sqlite ssl tk xml -bluetooth -build -examples -hardened -ipv6 -libressl -test -wininst) 3.8.6-r1(3.8)^t([2021-01-24 23:28:48])(gdbm ncurses readline sqlite ssl tk xml -bluetooth -build -examples -hardened -ipv6 -libressl -test -wininst) 3.9.0-r1(3.9)^t([2021-01-24 23:31:53])(gdbm ncurses readline sqlite ssl tk xml -bluetooth -build -examples -hardened -ipv6 -libressl -test -wininst)

I can't understand why there are so many ways to control Python
nor which one users are supposed to use nor how to reconcile them.
I would be very happy simply to use 3.9 for all Python purposes.

Thanks again for your hard work on this + other areas of Gentoo.

--
========================,,============================================
SUPPORT ___________//___, Philip Webb
ELECTRIC /] [] [] [] [] []| Cities Centre, University of Toronto
TRANSIT `-O----------O---' purslowatcadotinterdotnet

On Tue, 2021-01-26 at 01:39 -0500, Philip Webb wrote:
> 210125 Micha? Górny wrote:
> > Changed eselect-python dep removal date to July 2021.
> > Not sure if there's a reason to display it to stable users today,
> > or delay until the stable request is actually filed.
>
> I've been using Gentoo since 2003 , happily enough most of the time ;
> I'm an ordinary desktop user without any special requirements.
> Python versions have been one of the reasons for the exceptions.
> I finally managed to remove 2.7 from my system yesterday.
>
> I do appreciate your work in this area,
> but I can make no sense of the news item below.

Thank you for your kind words. However, I don't really know if I can
help you. The news item is supposed to tell what's new. If I were to
keep explaining the basics, it'd become too long (and people are already
complaining that my items are getting too long). I think this falls
into 'if you don't know whether you need to read on, don't'.

>
> > Title: Python preference to follow PYTHON_TARGETS
> > Author: Micha? Górny <mgorny@gentoo.org>
> > Posted: 2021-01-24
> > Revision: 1
> > News-Item-Format: 2.0
> >
> > On 2021-02-01 stable users will switch to a new method of updating
> > the preferred Python versions that employs the configuration update
> > mechanism in order to follow PYTHON_TARGETS.
>
> What are "preferred Python versions" ? Why are they multiple, not one ?

It's the order in which the Python version used to run stuff are used.
There are multiple because not all impls are actually supported by
everything -- so if your top preference doesn't work, it goes for
the second top, etc.

> What is the "configuration update mechanism",

CONFIG_PROTECT / etc-update / dispatch-conf.

> how does it "follow PYTHON_TARGETS" & why are they both needed ?

I think this is explained below -- it generates python-exec.conf based
on PYTHON_TARGETS. Both are needed because we can't technically combine
both without putting a lot of effort to implement stuff that's going to
be slow and unreliable.

>
> > We will also deprecate app-eselect/eselect-python,
> > and it will stop being installed by default after 2021-07-01.
>
> Why has there been this 3rd method of managing Python versions ?
> Why might it still be needed by users ?

Historical reasons, as always. Backwards compatibility.

> > If you wish to use the newest Python version present
> > in your PYTHON_TARGETS, you only have to accept configuration changes.
>
> Why doesn't Python behave like most other packages,
> ie use the latest installed version ? Why does PYTHON_TARGETS exist ?
> Why are the "targets" ? -- it sounds as if they may not be achieved.

Because Python versions are not ABI-compatible, and old packages are
usually broken with new major Python releases. It takes a lot of
testing, patching, bumping to support it.

> What are the "configuration changes" ?
> Do you mean those in /etc/python-exec ?

Yes.

>
> > If you wish to customize the behavior, read on.
>
> I have no wish to customise Python. I don't use it to develop programs ;
> it is installed only as a requirement for other packages, eg Portage.
> I do use it for a small script to work as a CLI calculator.
> Given this, I won't comment on the rest of the news item,
> but it makes even less sense to me than the section above.

Then you don't have to do anything.

--
Best regards,
Micha? Górny