[Python-Dev] PEP 408 -- Standard library __preview__ package

[Michael Foord]

On 27/01/2012 14:37, Philippe Fremy wrote:
> Hi,
>
> A small comment from a user perspective.
>
> Since a package in preview is strongly linked to a given version of
> Python, any program taking advantage of it becomes strongly specific to
> a given version of Python.
>
> Such programs will of course break for any upgrade or downgrade of
> python version. To make the reason for the breakage more explicit, I
> believe that the PEP should provide examples of correct versionned usage
> of the module.
>
> Something along the lines of :
>
> if sys.version_info[:2] == (3, X):
> 	from __preview__ import example
> else:
> 	raise ImportError( 'Package example is only available as preview in
> Python version 3.X. Please check the documentation of your version of
> Python to see if and how you can get the package example.' )

A more normal incantation, as is often the way for packages that became 
parts of the standard library after first being a third party library 
(sometimes under a different name, e.g. simplejson -> json):

try:
     from __preview__ import thing
except ImportError:
     import thing

So no need to target a very specific version of Python.

Michael

>
> cheers,
>
> Philippe
> _______________________________________________
> Python-Dev mailing list
> Python-Dev at python.org
> http://mail.python.org/mailman/listinfo/python-dev
> Unsubscribe: http://mail.python.org/mailman/options/python-dev/fuzzyman%40voidspace.org.uk
>


-- 
http://www.voidspace.org.uk/

May you do good and not evil
May you find forgiveness for yourself and forgive others
May you share freely, never taking more than you give.
-- the sqlite blessing http://www.sqlite.org/different.html