[Python-Dev] PEP 408 -- Standard library preview package (original) (raw)

Michael Foord fuzzyman at voidspace.org.uk
Fri Jan 27 16:25:28 CET 2012

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.versioninfo[: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

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