[Python-ideas] PEP 426, YAML in the stdlib and implementation discovery

[Andrew Barnert]

From: Philipp A. <flying-sheep at web.de>
Sent: Friday, May 31, 2013 12:39 PM


> and that’s where my idea’s “strict API” comes into play: compatible implementations would *have to* pass a test suite and implement a certain API and comply with the standard.
>
>unsure if and how to test the latter (surely running a testsuite when something wants to register isn’t practical – or is it?)


After sleeping on this question, I'm not sure the best-implementation wrapper really needs to be that dynamic. There are only so many YAML libraries out there, and the set doesn't change that rapidly. (And the same is true for dbm, ElementTree, etc.) 

So, maybe we just put a static list in yaml, like the one in dbm (http://hg.python.org/cpython/file/3.3/Lib/dbm/__init__.py#l41): _names = ['pyyaml', 'yaml.yaml'] If a new implementation reaches maturity, it goes through some process TBD, and in 3.5.2, we change that one line to _names = ['pyyaml', 'yayaml', 'yaml.yaml']. And that's how you "register" a new implementation.

The only real downside I can see is that some people might stick to 3.5.1 for a long time after 3.5.2 is released (maybe because it comes pre-installed with OS X 10.9 or RHEL 7.2 ESR or something), but still want to accept yayaml. If that's really an issue, someone could put an "anyyaml" backport project on PyPI that offered the latest registered name list to older versions of Python (maybe even including 2.7).

Is that good enough?