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

Nick Coghlan ncoghlan at gmail.com
Sun Jan 29 02:33:21 CET 2012

On Sun, Jan 29, 2012 at 3:15 AM, Guido van Rossum <guido at python.org> wrote:

Hm. You could do this just as well without a preview package. You just flag the module as experimental in the docs and get on with your life.

We have some experience with this in Google App Engine. We used to use a separate "labs" package in our namespace and when packages were deemed stable enough they were moved from labs to non-labs. But the move always turned out to be a major pain, causing more breakage than we would have had if we had simply kept the package location the same but let the API mutate. Now we just put new, experimental packages in the right place from the start, and put a loud "experimental" banner on all pages of their docs, which is removed once the API is stable. There is much less pain now: while incompatible changes do happen for experimental package, they are not frequent, and rarely earth-shattering, and usually the final step is simply removing the banner without making any (incompatible) changes to the code. This means that the final step is painless for early adopters, thereby rewarding them for their patience instead of giving them one final kick while they sort out the import changes. So I do not support the preview package. I think we're better off flagging experimental modules in the docs than in their name. For the specific case of the regex module, the best way to adoption may just be to include it in the stdlib as regex and keep it there. Any other solution will just cause too much anxiety.

I'm willing to go along with that (especially given your report of AppEngine's experience with the "labs" namespace).

Can we class this as a pronouncement on PEP 408? That is, "No to adding a preview namespace, but yes to adding regex directly for 3.3"?

Regards, Nick.

-- Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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