Python 3 compatibility update to Python guidelines

[Ville Skyttä]

https://fedoraproject.org/wiki/Packaging:Python

%{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
distutils.sysconfig import get_python_lib; print get_python_lib()")}

%{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
distutils.sysconfig import get_python_lib; print get_python_lib(1)")}


These no longer work with Python 3 due to "print" changes.  They should be 
replaced with something like these that work with both Python 2 and 3 (already 
done in spectemplate-python.spec in rpmdevtools git):

%{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
distutils.sysconfig import *; import sys; 
sys.stdout.write(get_python_lib())")}

%{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
distutils.sysconfig import *; import sys; 
sys.stdout.write(get_python_lib(1))")}

[David Malcolm]

On Sat, 2009-10-17 at 13:33 +0300, Ville Skyttä wrote:
>  https://fedoraproject.org/wiki/Packaging:Python
>  
>  %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
>  distutils.sysconfig import get_python_lib; print get_python_lib()")}
>  
>  %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
>  distutils.sysconfig import get_python_lib; print get_python_lib(1)")}
>  
>  
>  These no longer work with Python 3 due to "print" changes.  They should be 
>  replaced with something like these that work with both Python 2 and 3 (already 
>  done in spectemplate-python.spec in rpmdevtools git):
>  
>  %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
>  distutils.sysconfig import *; import sys; 
>  sys.stdout.write(get_python_lib())")}
>  
>  %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
>  distutils.sysconfig import *; import sys; 
>  sys.stdout.write(get_python_lib(1))")} 
At first glance, yes, the change you suggest does generalize those
fragments of python code so they work with both python 2 and python 3
(it removes the trailing newline implicitly generated by "print", but
AIUI that's getting discarded in the macro handling)

However, I think it's going to be a long time until it's sane to make
%{__python} be python 3 rather than python 2.  I'm hoping we will have
parallel-installable python 2 and python 3 stacks [1], with separate
packages, probably separate srpms, so perhaps we need alternative
formulations where we define python3_sitelib and python3_sitearch?  Not
sure yet.

Your proposed change does ease migration, so a cautious "+1" from me.

Dave
[1] https://fedoraproject.org/wiki/Features/Python3F13

[David Malcolm]

On Sat, 2009-10-17 at 10:36 -0400, David Malcolm wrote:
>  On Sat, 2009-10-17 at 13:33 +0300, Ville Skyttä wrote:
>  > https://fedoraproject.org/wiki/Packaging:Python
>  > 
>  > %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
>  > distutils.sysconfig import get_python_lib; print get_python_lib()")}
>  > 
>  > %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
>  > distutils.sysconfig import get_python_lib; print get_python_lib(1)")}
>  > 
>  > 
>  > These no longer work with Python 3 due to "print" changes.  They should be
>
>  > replaced with something like these that work with both Python 2 and 3 (already 
>  > done in spectemplate-python.spec in rpmdevtools git):
>  > 
>  > %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
>  > distutils.sysconfig import *; import sys; 
>  > sys.stdout.write(get_python_lib())")}
>  > 
>  > %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
>  > distutils.sysconfig import *; import sys; 
>  > sys.stdout.write(get_python_lib(1))")}
>   
[snip]

>  Your proposed change does ease migration, so a cautious
> "+1" from me. 
[snip]

Did the change to the guidelines happen, and did the rpmdevtools
template get updated?

[Ville Skyttä]

On Friday 30 October 2009, David Malcolm wrote:

>  Did the change to the guidelines happen, 
Not yet I suppose, at least it's not in 
https://fedoraproject.org/wiki/Packaging:Python

>  and did the rpmdevtools template get updated? 
Yes, but there's no release out with the updated one yet.
http://git.fedoraproject.org/git/rpmdevtools.git/?p=rpmdevtools.git;a=com...

[Toshio Kuratomi]

On Sat, Oct 17, 2009 at 01:33:29PM +0300, Ville Skyttä wrote:
>  https://fedoraproject.org/wiki/Packaging:Python
>  
>  %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
>  distutils.sysconfig import get_python_lib; print get_python_lib()")}
>  
>  %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
>  distutils.sysconfig import get_python_lib; print get_python_lib(1)")}
>  
>  
>  These no longer work with Python 3 due to "print" changes.  They should be 
>  replaced with something like these that work with both Python 2 and 3 (already 
>  done in spectemplate-python.spec in rpmdevtools git):
>  
>  %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from 
>  distutils.sysconfig import *; import sys; 
>  sys.stdout.write(get_python_lib())")}
>  
>  %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from 
>  distutils.sysconfig import *; import sys; 
>  sys.stdout.write(get_python_lib(1))")}
>   
Any reason not to do it this way?

%{!?python_sitelib: %global python_sitelib %(%{__python} -c "from.
distutils.sysconfig import *; print (get_python_lib())")}

%{!?python_sitearch: %global python_sitearch %(%{__python} -c "from.
distutils.sysconfig import *; print(get_python_lib(1))")}

Also, dmalcolm, could we get these macros into the python and python3 (when
revewied) package so we don't have to add them as boilerplate to every
package?

-Toshio

[Ville Skyttä]

On Saturday 31 October 2009, Toshio Kuratomi wrote:

>  Any reason not to do it this way?
>  
>  %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from.
>  distutils.sysconfig import *; print (get_python_lib())")}
>  
>  %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from.
>  distutils.sysconfig import *; print(get_python_lib(1))")} 
Assuming the "." after "from" is unintentional in both and that there
should 
be a space after "print" and before "(" in the latter, that seems to
work too.  
It does look a bit hackish to me though.

>  Also, dmalcolm, could we get these macros into the python and python3
> (when
>  revewied) package so we don't have to add them as boilerplate to every
>  package? 
That would be good, but until they're in at least the latest EL as well, I 
intend to keep them also in the rpmdevtools spec template.

[Toshio Kuratomi]

On Tue, Nov 03, 2009 at 08:55:24AM +0200, Ville Skyttä wrote:
>  On Saturday 31 October 2009, Toshio Kuratomi wrote:
>  
>  > Any reason not to do it this way?
>  > 
>  > %{!?python_sitelib: %global python_sitelib %(%{__python} -c "from.
>  > distutils.sysconfig import *; print (get_python_lib())")}
>  > 
>  > %{!?python_sitearch: %global python_sitearch %(%{__python} -c "from.
>  > distutils.sysconfig import *; print(get_python_lib(1))")}
>  
>  Assuming the "." after "from" is unintentional in both
>  
Yeah, copy and paste from an editor that displays trailing spaces  Sorry.

>  and that there should 
>  be a space after "print" and before "(" in the latter, that seems to
> work too.  
>  It does look a bit hackish to me though.
>   
So.. this seems to be a matter of viewpoint.  From a python3 standpoint,
print is now a function so doing::
  print(get_python_lib())

Seems perfectly normal whereas import sys; sys.stdout.write() looks hackish.

From a python2 standpoint where print is a keyword the extra space makes
more sense::
  print (get_python_lib())

but does indeed look a little hackish. (Since you're either using
parenthesis in a throwaway manner here, or worse, with multiple values
making a tuple [which won't print correctly -- although py2.6+ has from
__future__ import print_function which makes that work.]).

Since this is purely stylistic (for python_sitelib definition, any of these
ways work) we're just deciding whether we want to write these as python3
that's backwards compatible or python2 that's forward compatible.  If we get
these into the python/python3 packages, I don't care at all.  If they stay
in the Guidelienes alone, I'd go with the python3 viewpoint since we're
starting the migration towards that.

>  > Also, dmalcolm, could we get these macros into the python and
> python3 (when
>  > revewied) package so we don't have to add them as boilerplate to every
>  > package?
>  
>  That would be good, but until they're in at least the latest EL as well, I 
>  intend to keep them also in the rpmdevtools spec template.
>   
+1

-Toshio

[Ville Skyttä]

On Tuesday 03 November 2009, Toshio Kuratomi wrote:

>  Since this is purely stylistic [...] 
I actually thought it wasn't purely stylistic and that without the space 
"print('foo')" would blow up with Python 2, but I was wrong, sorry about
that.  
I don't care if the space is there or not or sys.stdout.write is used instead, 
will follow in rpmdevtools whatever ends up in the guidelines as long as it 
works for both Python 2 and 3.

[Toshio Kuratomi]

On Tue, Nov 03, 2009 at 09:06:10PM +0200, Ville Skyttä wrote:
>  On Tuesday 03 November 2009, Toshio Kuratomi wrote:
>  
>  > Since this is purely stylistic [...]
>  
>  I actually thought it wasn't purely stylistic and that without the space 
>  "print('foo')" would blow up with Python 2, but I was wrong, sorry
> about that.  
>  I don't care if the space is there or not or sys.stdout.write is used instead, 
>  will follow in rpmdevtools whatever ends up in the guidelines as long as it 
>  works for both Python 2 and 3.
>  
Updated:
https://fedoraproject.org/wiki/Packaging:Python#System_Architecture

-Toshio