Re: [Rpm-maint] [rpm-software-management/rpm] Change the shebang of pythondistdeps.py to Python 3 (#212)

[torsava]

> This makes no sense, /usr/bin/python is usually the linked to the binary of 
> the default python version in use on distros, so hardcoding the version makes 
> no sense.

That is a common misconception. While some distros went ahead and switched 
`/usr/bin/python` to Python 3, most notably Arch Linux, most are keeping it 
pointing to Python 2 and will continue to do so at least until Python 2 EOL in 
2020. Upstream Python issued a recommendation to that effect as well: [PEP 394 
-- The "python" Command on Unix-Like 
Systems](https://www.python.org/dev/peps/pep-0394/#abstract)

So while most distros that will be using the latest RPM already switched to 
Python 3 being default, the binary `/usr/bin/python` still points to Python 2. 
That means that most distros will need to patch this shebang to 
`/usr/bin/python3` before deploying.

I propose that we switch the shebang to explicitly Python 3 by default. There 
possibly might be some distros that will be using the latest RPM version but 
still haven't switched to Python 3 being default (and they will need to patch 
this shebang back to Python 2), but I'd wager it will be a minuscule number 
compared to Python 3–default distros.

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Re: [Rpm-maint] [rpm-software-management/rpm] Triple operator for conditional shortcut (#115)

[pavlinamv]

I do not see any possibility how to define sensible syntax of the triple 
operator, without possible causing problems for macros %{?condition:true} and 
%{!?condition:false}. Thus I think that adding this macro without additional 
changes is not a good idea.

The syntax of the macro should start "%{?condition:" or "%{!?condition:"
But then there is a problem with next separator operator:
  E.g if we define syntax
   %{?condition:true!false},
  where separator operator is the first '!' after ':', which is not nested in 
{} or in ()
  it will change interpretation of macros like
   %{?write_errors: You did not respond! It is a mistake.}
  which will change from its original meaning 
  if "write_errors" is defined, then write "You did not respond! It is a 
mistake."
  to 
  if "write_errors" is defined, then write "You did not respond" else write " 
It is a mistake."
 
If we change separator operator from "!" to another character it will not help 
us a lot. The mentioned type of mistake will still occur. The only characters 
which are different from rpm point of view are  "{", "}", "(", ")". To use some 
of them is not a good choice too. The triple operator will look very weird and 
probably another type of problems occur.

Similarly for a separator operator defined as a sequence of chars.

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Re: [Rpm-maint] [rpm-software-management/rpm] Change the shebang of pythondistdeps.py to Python 3 (#212)

[proyvind]

First of all, while PEP 394 recommends this, it's not what's common practice 
amongst distros, where Arch not even being a RPM based distro makes it less 
relevant.

I know of no rpm based distros where /usr/bin/python isn't pointing to the 
default python interpreter binary version. Also using shell aliases to set the 
default binary to use isn't really a good idea as these aliases are internal to 
the shell instance itself only in contrast to environment variables and paths.

While python upstream plans to EOL python 2 in two years, distributions 
interest and priorities aren't the same. The usual approach is to either only 
keep python 2 around untill everything still depending on and not ported to 
py3k and/or at least not install any python2 packages by default, where if 
/usr/bin/python had to point to python2, that would leave one in a tricky 
situation if only python 3 is installed.

However, if you really think this is a necessity (where forcing distros still 
using python2 to patch the shebang themself would be considered less acceptable 
than not adhering to PEP 394), the patch betlow would be the more proper way to 
achieve your goal.

This one also ensures that this $PYTHON is used for both %__python and the 
python bindings as well.
``
From 2ca7cc81357fc61fd017bae0cf3c109345224216 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Per=20=C3=98yvind=20Karlsen?= 
Date: Thu, 4 May 2017 14:30:54 +0200
Subject: [PATCH] allow to set default python interpreter with $PYTHON during
 ./configure

---
 configure.ac| 3 ++-
 python/setup.py.in  | 2 +-
 scripts/{pythondistdeps.py => pythondistdeps.py.in} | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)
 rename scripts/{pythondistdeps.py => pythondistdeps.py.in} (99%)

diff --git a/configure.ac b/configure.ac
index b41a4c9..0f8c202 100644
--- a/configure.ac
+++ b/configure.ac
@@ -129,7 +129,7 @@ AC_MSG_CHECKING(old version of patch)
 
 AC_PATH_PROG(__PERL, perl, /usr/bin/perl, $MYPATH)
 AC_PATH_PROG(__PGP, pgp, /usr/bin/pgp, $MYPATH)
-AC_PATH_PROG(__PYTHON, python, /usr/bin/python, $MYPATH) 
+AC_PATH_PROG(__PYTHON, [$PYTHON python], $PYTHON, [/usr/bin/python], $MYPATH)
 AC_PATH_PROG(__RM, rm, /bin/rm, $MYPATH)
 AC_PATH_PROG(__RSH, rsh, /usr/bin/rsh, $MYPATH)
 AC_PATH_PROG(__SED, sed, /bin/sed, $MYPATH)
@@ -1016,5 +1016,6 @@ AC_CONFIG_FILES([Makefile
tests/Makefile
plugins/Makefile
python/setup.py
+   scripts/pythondistdeps.py
   ])
 AC_OUTPUT
diff --git a/python/setup.py.in b/python/setup.py.in
index 87c7358..534688b 100644
--- a/python/setup.py.in
+++ b/python/setup.py.in
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!@__PYTHON@
 
 from distutils.core import setup, Extension
 import subprocess
diff --git a/scripts/pythondistdeps.py b/scripts/pythondistdeps.py.in
similarity index 99%
rename from scripts/pythondistdeps.py
rename to scripts/pythondistdeps.py.in
index 36590ba..408a1de 100755
--- a/scripts/pythondistdeps.py
+++ b/scripts/pythondistdeps.py.in
@@ -1,4 +1,4 @@
-#!/usr/bin/python3
+#!@__PYTHON@
 # -*- coding: utf-8 -*-
 #
 # Copyright 2010 Per Øyvind Karlsen 
-- 
2.10.2



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Re: [Rpm-maint] [rpm-software-management/rpm] Change the shebang of pythondistdeps.py to Python 3 (#212)

[ニール・ゴンパ]

>> Welcome back to 2017, Mandriva is dead ;)

> Ah, that explains it :)

Mageia is still here, and we follow PEP 394. 

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Re: [Rpm-maint] [rpm-software-management/rpm] Change the shebang of pythondistdeps.py to Python 3 (#212)

[proyvind]

OpenMandriva uses python 3 as default, with /usr/bin/python pointing to python3.
AFAIK Mageia doesn't intentionally follow PEP 394 as much as it rather hasn't 
switched to python3 as it's default yet, where ie. python packages prefixed 
with python- are python 2, while python 3 packages are prefixed with python3-...


As distros completes their migration to python 3 and no python 2 package 
installed on system, any py3k compatible script from packages in distro using 
/usr/bin/python as shebang will be left broken, for which there surely are 
quite a few.

PEP 394 doesn't take the flipped situation py3k compatible scripts with 
/usr/bin/python as shebang into reasonable enough consideration, where such 
scripts are already and growingly in majority.

For old sys admin scripts, more realistic/sane scenarios would be for the sys 
admins running something non-cutting edge releases like RHEL/CentOS etc.



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Re: [Rpm-maint] [rpm-software-management/rpm] Change the shebang of pythondistdeps.py to Python 3 (#212)

[proyvind]

the philosophical discussion regarding is anyways rather moot, but the patch 
from my earlier comment should anyways be sufficient to address it properly. :)

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