Re: cleanups with long-term benefits (was Re: [PATCH] schemas: Add vim modeline)

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> On 03/08/20 13:28, Markus Armbruster wrote:
>>>> We could remove them from the QAPI schema language.  Flag day, and
>>>> git-blame becomes pretty much useless for a couple of years.
>>> Is that a nack or a "whatever"?
>> It's "is this really worth the trouble?"  I guess that's halfway between
>> NAK and whatever, ready to be moved in either direction by arguments :)
>
> In general it seems like a good idea to use a standard file format and
> not "a standard file format except for two characters". :)  We also
> wouldn't be having discussions on editors.

No argument.  But towards which standard file format should the schema
evolve?

* Standard JSON: no comments, no go

* JSON with # comments: need to change strings from ' to "

* JavaScript: need to change comments from # to //

* Python: may want to switch bool literals from true, false to True,
  False

> That said, after a bit more research I'm skeptical about the possibility
> of using an off-the-shelf parser because most of them either don't
> support comments, or are based on YAJL which simply discards comments.
>
> Since '//' comments are harder to parse than "#" comments, this would
> actually _add_ code instead of removing it.  Also since our doc comment
> syntax uses "##" as a delimiter, we'd have to bikeshed what the doc
> comments would look like ("//!", "///", etc.).

Doc comments don't have to be comments in the schema language.  They
could be doc strings.  Requires decent support for long strings, which
JSON does not provide.

> This means the two parts might be considered separately:
>
> - replacing single-quote with double-quote strings
>
> - replacing # comments with //

If all we want is decent editor support out of the box, then rename to
.py, and drop the modelines.  No merge conflicts, no git-blame
pollution.

To make the .py files actual Python, additionally rename the bool
literals.  Much, much less churn than massaging all strings or all
comments.