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

Stefan Drees stefan at drees.name
Wed Jun 5 10:08:40 CEST 2013 
On 05.06.13 09:53, Andrew Barnert wrote:
> From: Stefan Drees ... Sent: Wednesday, June 5, 2013 12:31 AM ...
>> while some text of my previous reply to this mail (which is already in the
>> archives, but has not yet reached my mailbox again) may be interesting read and
>> the YAML spec might really profit from some rewriting to clarify the JSON-YAML
>> relation, I overlooked "production 53" in [1]  and the notion of what
>> YAML uses a superset of C escape sequences realy means =(
>
> Perfect timing; right after I hit "send", I see your followup…
> That'svery different. Never mind. :)

mistakes are so effficient in getting attention ;-)


> Still, despite your mistake, your raised the point that the version of
> YAML implemented by PyYAML (YAML 1.1) is not a strict superset of JSON,
> and that may be worth addressing. Would PyYAML have to upgrade to 1.2,
> or at least to 1.1 plus enough 1.2 changes to make it a strict superset
> of JSON, to be worth adding to the stdlib? Or would it be reasonable to
> say "Don't use the yaml module to parse JSON, dummy"?

Someone (I think the OP of the cited pyyaml issue #11) noted, that they 
receive a mix of JSON and YAML messages over some interface and tried to 
handle that by simply digesting through a YAML parser.

In the light of the wide deployment of YAML v1.1 in tools I would at 
least for some time resort to your latter alternative, maybe checking 
the last word against some applicable CoC ;-)

But, I will mainly think a bit or two more about what the price for this 
JSONesque attitude actually is. If you're so inclined, please repeat 
after me: "You can't simply delegate processing of a double quoted JSON 
string to C functions expecting C escape sequences" (and it is not only 
production 53 ...)

I am all for a YAML parser inside python stdlib - at some time - with 
clear expectations on conformance, performance and "expectation 
management" for the users thereof. The latter because I am convinced, 
that as soon as something is part of the stdlib, people will start using 
it to also "learn" from it's API and "terms" about the domain handled. 
So terms, API and error messages should all be conforming to YAML spec 
Version 1.2+errata and well "settled".

Glossary (for dummies like me :)

CoC: Code of Conduct.

All the best,
Stefan.
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