[Python-Dev] Status of PEP 397 - Python launcher for Windows

[Mark Hammond]

On 18/02/2012 11:08 PM, martin at v.loewis.de wrote:
>
> Zitat von Mark Hammond <skippy.hammond at gmail.com>:
>
>> I'm wondering what thoughts are on PEP 397, the Python launcher for
>> Windows. I've been using the implementation for a number of months now
>> and I find it incredibly useful.
>
> I wonder what the rationale for the PEP (as opposed to the rationale
> for the launcher) is - why do you need to have a PEP for it? As
> written, it specifies some "guidelines" that some software package
> of yours might adhere to. You don't need a PEP for that, just write
> the software and adhere to the guidelines, possibly putting them into
> the documentation.
>
> A PEP needs to have controversial issues, or else there would not
> have been a point in writing it in the first place. Also, it needs
> to concern CPython, or the Python language, else it does not need to
> be a *P*EP.

The launcher was slightly controversial when the pep was initially 
written 12 months ago.  If you believe the creation of the PEP was 
procedurally incorrect I'm happy to withdraw it - obviously I just want 
the launcher, with or without a PEP.  Alternatively, if you think the 
format of the PEP needs to change before it can be accepted, then I'm 
happy to do that too if you can be very specific about what you want 
changed.  If you mean something else entirely then please be very 
specific - I admit I'm not clear on the point of your message at all.

>
> To be a proper PEP, you need to include these things:
> - what is the action that you want to see taken?
> - what is the Python version (or versions) that you
> want to see the action taken for?
> - what alternative actions have been proposed, and what
> are (in your opinion, and the opinion of readers) pros
> and cons of each action?
>
> Assuming you are proposing some future action for CPython,
> I'm opposed to the notion that the implementation of the
> launcher is the specification. The specification needs to be
> in the PEP. It may leave room, in which case the remaining
> details need to be specified in the documentation.

I'm really not sure what you are trying to say here.  That the PEP 
should remove all references to an implementation specification, or that 
the PEP simply should be withdrawn?  As above, I don't care - I just 
want the launcher with the least amount of bureaucracy possible.

> A critical question (IMO) is the question how the launcher
> gets onto systems. Will people have to download and install
> it themselves, or will it come as part of some Python
> distribution?

This is addressed in the PEP: "The launcher will be distributed with all 
future versions of Python ..."

> If it comes with the Python distribution,
> how get multiple copies of the launcher coordinated?

This may not be specified as well as it could, but: "Future versions of 
the launcher should remain backwards compatible with older versions, so 
later versions of Python can install an updated version of the launcher 
without impacting how the previously installed version of the launcher 
is used."

> Also: what's the name of the launcher? How can I actually use
> it?

This too is there: "The console launcher will be named 'py.exe' and the 
Windows one named 'pyw.exe'" and there is discussion of the command-line 
args.

Mark