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

[Terry Reedy]

On 3/6/2011 8:18 PM, Mark Hammond wrote:

> To be clear, I was suggesting that using .bat files in system32 is a
> close analogy to the *nix situation - I didn't mean to advocate for it
> to actually happen :) Further, I see the creation of a python3.exe in
> the Python install directory as quite different than the *nix situation
> (where the 'python3' link is not in the install dir, but instead in a
> 'system' dir). IOW, I was trying to point out the solution to the
> problem on *nix doesn't translate that well to Windows, so Windows
> should not be considered as part of this PEP. That isn't to suggest
> Windows should not be considered at all.
>
> That said though, I'm only -0 on python2.exe/python3.exe - I don't think
> it will hurt, but also don't think it will help that much in practice.
> It may also turn out to be unnecessary should a "complete" solution be
> implemented - eg, a "python launcher" which (a) read the shebang lines
> and (b) allowed something like "python -3" on the command-line would
> render both python3.exe and requests to have multiple installed Python
> versions on the PATH redundant.

I completely support Mark's repeated request that Windows be left out of 
the PEP. I'm sure that Guido himself would say that 'include Windows' 
was meant to be qualified with 'if reasonable and sensible'.

To summarize why not 'reasonable and sensible':

1. The solution in the PEP depends on the operating system respecting 
the shebang line. Windows does not, so the PEP is not appicable, unless 
we write a launcher that does. But that is outside the scope of the PEP.

2. There is something of a consensus on most of the PEP as is, but less 
for Windows. The Unix-like PEP should be finalized, approved, and 
implemented now. Windows can wait.

3. As a Windows user, I would like a *complete* solution that cannot all 
be part of PEP. It makes no sense to incorporate a partial solution that 
may be obsoleted by a real Windows install PEP.

4. I think a launcher may be the best idea. If so, other parts of a 
complete solution will flow from how that is written.

5. The PEP authors cannot write a Windows sub-PEP, so it would require 
different authors and effectively be a half-PEP in itself anyway. The 
implementations of the currently PEP and a Windows upgrade would mostly 
be disjoint also, both in terms of code and authors.

-- 
Terry Jan Reedy