[Python-Dev] Support the /usr/bin/python2 symlink upstream

[Michael Foord]

On 04/03/2011 13:21, Nick Coghlan wrote:
> On Fri, Mar 4, 2011 at 10:59 PM, Michael Foord
> <fuzzyman at voidspace.org.uk>  wrote:
>> Should any of this also apply to Mac OS X and Windows?
> Any platform that considers itself "unix-like" in this context can
> decide to follow it, we aren't fussy (e.g. Cygwin and the *nix-y
> aspects of OS X). The main point of the PEP is to get a consensus
> recommendation out of python-dev as to the best way forward (and I
> think Kerrick did a good job of summarising the position that has been
> expressed in this thread).
>
Right, but the pep doesn't address those issues for some fairly major 
platforms.

> More generally, Windows and Mac OS X developers seem to be happier
> with the idea of bundling a Python interpreter inside the application
> than traditional *nix style platforms. This is a PITA for the system
> maintainer when it comes time to handle security vulnerabilites, but
> certainly more convenient when upgrading the default Python install.
>

However on Mac OS X at least *scripts* have the same issue (what to put 
in the shebang line).

>> Note that we *do* have alternative distributors [1] of Python for these
>> platforms who may wish to follow any recommendations we have for 2.7, even
>> if we don't modify those installers for our own distributions.
> The really tricky part on Windows is handling file associations. I
> think we're just doomed on that front, unless we want to start
> supporting separate .py2 and .py3 extensions (and adding *that* in a
> maintenance release would be a far cry from just adding another
> symlink).
>
> The lack of near-universal symlink support on Windows filesystems is
> also an issue - we would have to duplicate files like python.exe and
> pythonw.exe on non-NTFS filesystems in order to provide them under
> alternative names.
>
> For *nix, I think there is a simple way forward that is an improvement
> over where things stand now. For Windows, I don't think we can do much
> better than the status quo and for Mac OS X... I think Apple will do
> whatever Apple feel like doing :)
>

Right, but on Mac OS X we do put a "python3" on the path but not a 
"python2". We also create "python2.x" and "python3.x" variants. So the 
same issues exist yet the pep

On Windows we only have a "python.exe" I believe, but if the user does 
put their Python installs on the path then we *could* usefully create 
"python2.exe" and "python3.exe" for them. I don't see that duplicating 
these binaries on the filesystem is an issue. File associations is just 
unsolvable on Windows, so it isn't something we can address or should 
worry about. (Actually a stub python.exe that looks at the shebang line 
and then delegates to the appropriate pythonX.Y.exe would be a 
possibility but I'm not volunteering to write it.)

All the best,

Michael

> Cheers,
> Nick.
>


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