[Python-Dev] PEP 394 request for pronouncement (python2 symlink in *nix systems)

[Ned Deily]

In article <4F3CD403.7070102 at v.loewis.de>,
 "Martin v. Lowis" <martin at v.loewis.de> wrote:

> > There are two issues that I know of for OS X.  One is just getting a 
> > python2 symlink into the bin directory of a framework build.  That's 
> > easy.
> 
> Where exactly in the Makefile is that reflected? ISTM that the current
> patch already covers that, since the framwork* targets are not concerned
> with the bin directory.

When a framework build is enabled in configure, several additional 
targets from Mac/Makefile are called from the main Makefile.  The 
creating of the links in the framework bin directory and in $prefix/bin 
(/usr/local/bin) are handled there.  (See the checked in patch for 2.7 
for gory details: http://hg.python.org/cpython/rev/499796937b7a)
 
> > The other is managing symlinks (python, python2, and python3) 
> > across framework bin directories; currently there's no infrastructure 
> > for that.  That part will probably have to wait until PyCon.
> 
> What is the "framework bin directory"? The links are proposed for
> /usr/local/bin resp. /usr/bin. The proposed patch already manages
> these links across releases (the most recent install wins).

The framework bin directory is a bin directory within a framework.  The 
default location for 2.7 is:

    /Library/Frameworks/Python.framework/Versions/2.7/bin

This is where the python executable, aux programs like idle, 2to3, 
pydoc, python-config, as well as all Distutils-installed scripts go.  
Mac/Makefile and the Mac installer each optionally create symlinks from 
/usr/local/bin (default) to the items in the framework bin directory at 
build or install time for the standard items but not for subsequent 
Distutils-installed scripts.  Normally, the /usr/local/bin links are not 
needed with framework builds as the framework bin directory is added to 
the user's $PATH during installation.
 
> If you are concerned about multiple feature releases: this is not an
> issue, since the links are just proposed for Python 2.7 (distributions
> may also add them for 2.6 and earlier, but we are not going to make
> a release in that direction).

It is more of an issue for multiple Python 3 versions.  But the whole 
mechanism of managing multiple framework versions (2 and/or 3) is messy 
right now.  But that's a separate topic that I plan to address later.  
As for now, I believe all that is needed for PEP 394 is now checked-in.

-- 
 Ned Deily,
 nad at acm.org