Eric Blake <ebl...@redhat.com> writes:
> On 04/01/2015 03:33 AM, Markus Armbruster wrote:
>
>>>> Longhand:
>>>>
>>>> # mandatory
>>>> 'name': { 'type': 'str' }
>>>> # optional, with a default
>>>> 'flag': { 'type': 'bool', 'default': true }
>>>> # optional, no default
>>>> 'string': { 'type': 'str', 'default': null }
>>>>
>>>> Presence of 'default' implies optional.
>>>>
>>>> Equivalent shorthand, if any:
>>>>
>>>> 'name': 'str'
>>>> '*string': 'str'
>>>
>>> A nice shorthand for defaults would be:
>>>
>>> '*name': 'str' = 'default'
>>>
>>> Though that would be neither valid JSON nor Python any more. Do we
>>> actually rely on this property anywhere or is it only parsed by the QAPI
>>> generator anyway and we can extend the language in such ways?
>>
>> I guess JSON / Python was chosen as QAPI schema language to save us the
>> bother of defining a syntax and building the tools to work with it, like
>> an Emacs mode. JSON's not exactly my favourite choice, but at least
>> it's not XML.
>>
>> What we have now isn't JSON, but it's still a subset of Python, and the
>> Python tools work. If we go beyond Python, they'll break.
>
> Well, we were a subset of Python, until this patch added true, false,
> and null (the Python way would have been True, False, and None). We are
> also similar to JSON5, http://json5.org/
>
> Among other things, JSON5 allows trailing commas, allows unquoted keys
> in a dictionary, allows single-quoted strings, and allows C-style comments.
I'm open to consider adopting it once the dust settles.
>> If we decide to sacrifice these tools for readability, then we can just
>> as well replace the syntax entirely. Preferably by something where I
>> don't have to put every identifier in quotes.
>>
>> In short, you're welcome to hack up qapi.py some more for schema
>> readability, but either keep Emacs Python mode working, or provide a
>> replacement :)
>
> Since we're not quite python or JSON, we've already rolled our own
> parser; so rewriting QAPI to use a syntax of our own choosing is not
> that much of a leap.
Point taken.
> But not for this series.
Certainly.
