Re: [Qemu-devel] [PATCH v4 2/3] qapi: Add a primitive to include other files from a QAPI schema file

[Benoît Canet]

The Friday 14 Mar 2014 à 21:24:38 (+0100), Lluís Vilanova wrote :
> Benoît Canet writes:
> 
> > The Thursday 13 Mar 2014 à 19:05:12 (+0100), Lluís Vilanova wrote :
> >> Eric Blake writes:
> >> 
> >> > On 03/13/2014 09:33 AM, Benoît Canet wrote:
> >> >>> We certainly can't do without comments.
> >> >>> 
> >> >>> JSON is designed for easy data exchange, but we use it as programming
> >> >>> language syntax.  Its restrictions make sense for easy data exchange,
> >> >>> but hurt our use.  We're not the first ones experiencing that pain:
> >> >>> http://json5.org/
> >> >>> 
> >> >>> No idea how much momentum this JSON5 thingy has...
> >> 
> >> > If we 's,#,//,', our comments magically fall in line with JSON5 syntax;
> >> > everything else in our files is already compliant with JSON5.
> >> 
> >> >>> 
> >> >>> Switch to JSON5 and call it qapi-schema.json5?
> >> 
> >> > This actually seems like a rather nice idea - but due to our choice of
> >> > comments, it means rewriting the bulk of the file and tweaking our 
> >> > parser.
> >> 
> >> >>> 
> >> >> 
> >> >> Hmm don't we want something that python and other language know how to 
> >> >> parse out
> >> >> of the box ? Or will we write yet another delicate work of art to parse 
> >> >> it ?
> >> 
> >> > Our existing parser would only need to learn a new comment syntax to
> >> > parse the subset of JSON5 that we currently actually use.  Parsing FULL
> >> > JSON5 would mean also learning about trailing commas, unquoted names in
> >> > name:value pairs, multiline strings, and alternative numeric
> >> > representations.  But a point made on the JSON5 page is that ES5
> >> > JavaScript already parses JSON5, just as it already parses original JSON.
> >> 
> >> Another option is to bump QEMU requirements to python 2.6 or later. Then 
> >> we can
> >> use the json parser that comes with python. A simple pre-processing could
> >> eliminate the comments before passing them to the json package for loading 
> >> into
> >> python structures. The commands/enums/etc should also be elements of a 
> >> list for
> >> it to work (that must be either changed on the qapi files, or hackishly
> >> "injected" before parsing).
> >> 
> >> 
> >> Lluis
> 
> > I have an use case for this series.
> 
> > Lluis: Do you plan to respin this series ? Or should I do it ?
> 
> I was waiting for some other series to get merged, since they conflict. But I
> still did not change the "include" syntax.
> 
> I will probably not be able to get to this until May 1st.

Ok, I think I need the include feature more badly than you I will do it.

Best regards

Benoît

> 
> 
> Lluis
> 
> 
> -- 
>  "And it's much the same thing with knowledge, for whenever you learn
>  something new, the whole world becomes that much richer."
>  -- The Princess of Pure Reason, as told by Norton Juster in The Phantom
>  Tollbooth