[Python-Dev] Adding a toml module to the standard lib?

Paul Ganssle paul at ganssle.io
Wed May 15 08:57:57 EDT 2019

As someone involved in the packaging side of this, I think while we'd
eventually /appreciate/ a TOML parser in the standard library, I agree
with Victor that there's no rush, for two reasons:

1. setuptools and pip have a decent number of dependencies that we
vendor /anyway/, so vendoring one more is not a big deal.
2. We will be supporting older versions of Python for some time to come,
so we'd need to vendor a TOML-parser backport for several years before
we could actually use the one in the standard library.

I think /if/ a 1.0 version of the spec is going to be forthcoming (not
clear from the issue requesting it:
https://github.com/toml-lang/toml/issues/515 ), then it's worth waiting
at least a bit longer for it.

I also think it's probably worth asking the current maintainers of
TOML-parsing libraries if /they/ think it's time to adopt/adapt one of
their libraries for use in the standard library. They probably have a
better perspective on the stability and maturity of their codebases.


On 5/15/19 8:39 AM, Victor Stinner wrote:
> H Bastian,
> IMHO we should wait until the format reach version 1.0, since the
> stdlib has a slow release cycle (one release every 18 months). Too
> slow for a "fast moving" standard.
> In the meanwhile, I'm sure setuptools and pip will manage to install a
> toml parser/generator for their needs, as they already do :-)
> Victor
> Le mer. 15 mai 2019 à 12:50, Bastian Venthur <venthur at debian.org> a écrit :
>> On 15.05.19 11:33, Antoine Pitrou wrote:
>>> How stable is the TOML format?  Is it bound to change significantly in
>>> the coming years?
>>> If the format is stable enough, then I think it's a good idea.
>> The last update to the spec [1] was 10 months ago and added a few
>> features. The version before that was stable for more than 3 years. It
>> is also worth noting that he writes about the current version [2]:
>> "As of version 0.5.0, TOML should be considered extremely stable. The
>> goal is for version 1.0.0 to be backwards compatible (as much as humanly
>> possible) with version 0.5.0. All implementations are strongly
>> encouraged to become 0.5.0 compatible so that the transition to 1.0.0
>> will be simple when that happens."
>> That is of course no guarantee, but maybe the best we can hope for.
>> Cheers,
>> Bastian
>> [1]: https://github.com/toml-lang/toml/releases
>> [2]: https://github.com/toml-lang/toml
>> --
>> Dr. Bastian Venthur                                  http://venthur.de
>> Debian Developer                                 venthur at debian org
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