[Python-ideas] Possible Enhancement to py.exe Python Launcher

Steve Barnes gadgetsteve at live.co.uk
Fri Nov 24 01:25:01 EST 2017

Thanks Paul,

I had missed that section of PEP-0397 - the only options that are not 
covered are loading a local configuration from the current directory and 
the option to set a prompt/error if the python version is not specified 
on the command line or in the shebang.

Sorry for the noise!


On 23/11/2017 09:53, Paul Moore wrote:
> If I understand your proposal correctly, this is already possible, see
> https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.python.org%2Fdev%2Fpeps%2Fpep-0397%2F%23python-version-qualifiers&data=02%7C01%7Cgadgetsteve%40live.co.uk%7C6e858560c6504120febe08d532581be5%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636470276358104937&sdata=mgZCUtbRoEU6A0JHMoI1kvC49kPkWy7TYP6LgmCUCn0%3D&reserved=0
> The details are likely a little different than what you're proposing,
> but if they don't cover what you're trying to do, maybe you could give
> a more specific example of a use case that isn't currently possible?
> Paul
> On 23 November 2017 at 08:43, Steve Barnes <gadgetsteve at live.co.uk> wrote:
>> Following on from the discussions on pip I would like to suggest, (and
>> possibly implement), a minor change to the current py.exe python launcher.
>> Currently the launcher, when called without a version specifier,
>> defaults to the highest version on the basis of 3>2, x.11 > x.9, -64 >
>> -32 however this may not always be the most desirable behaviour.
>> I would like to suggest that it take a configuration value for the
>> default version to use, (and possibly a separate ones for pyw, & file
>> associations), honouring the following with the later overriding:
>> default - as current
>> system setting - from registry
>> user setting - from registry
>> user setting - from config file maybe %appdata%\pylauncher\defaults.ini
>> environment setting - from getenv
>> local setting - from .pyconfig file in the current directory.
>> Options would be the same format as the -X[.Y][-BB] format currently
>> accepted on the command line plus a --No-Py-Default option which would
>> always error out if the version to invoke was not specified.
>> I see this as potentially adding quite a lot of value for people with
>> multiple python versions installed and it could tie in quite well with
>> the possible use of py.exe as an entry point for tools such as pip.
>> It might also increase the awareness of the launcher as those who have
>> to stick with python 2 for the moment or in a specific context could set
>> the default to what they need but can always override.
>> --
>> Steve (Gadget) Barnes
>> Any opinions in this message are my personal opinions and do not reflect
>> those of my employer.
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Steve (Gadget) Barnes
Any opinions in this message are my personal opinions and do not reflect 
those of my employer.

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