From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37364) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YdJzW-0002rY-Sb for qemu-devel@nongnu.org; Wed, 01 Apr 2015 10:51:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YdJzR-0002cH-02 for qemu-devel@nongnu.org; Wed, 01 Apr 2015 10:51:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59090) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YdJzQ-0002c5-O4 for qemu-devel@nongnu.org; Wed, 01 Apr 2015 10:51:32 -0400 From: Markus Armbruster References: <1427227433-5030-1-git-send-email-eblake@redhat.com> <1427227433-5030-18-git-send-email-eblake@redhat.com> <20150331152359.GC4748@noname.redhat.com> <87sicl2akl.fsf@blackfin.pond.sub.org> <20150401083150.GB3593@noname.str.redhat.com> <87vbhgur9x.fsf@blackfin.pond.sub.org> <20150401095838.GD3593@noname.str.redhat.com> <87pp7ot8k7.fsf@blackfin.pond.sub.org> <20150401111711.GE3593@noname.str.redhat.com> Date: Wed, 01 Apr 2015 16:51:29 +0200 In-Reply-To: <20150401111711.GE3593@noname.str.redhat.com> (Kevin Wolf's message of "Wed, 1 Apr 2015 13:17:11 +0200") Message-ID: <87ego3sxzi.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v5 17/28] qapi: Allow true, false and null in schema json List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: famz@redhat.com, qemu-devel@nongnu.org, wenchaoqemu@gmail.com, lcapitulino@redhat.com Kevin Wolf writes: > Am 01.04.2015 um 13:03 hat Markus Armbruster geschrieben: >> Kevin Wolf writes: >> >> > Am 01.04.2015 um 11:33 hat Markus Armbruster geschrieben: >> >> Kevin Wolf writes: >> >> >> >> > Am 31.03.2015 um 22:09 hat Markus Armbruster geschrieben: >> >> >> Kevin Wolf writes: >> >> >> >> >> >> > Am 24.03.2015 um 21:03 hat Eric Blake geschrieben: >> >> >> >> From: Fam Zheng >> >> >> >> >> >> >> >> In the near term, we will use it for a sensible-looking >> >> >> >> 'gen':false inside command declarations, instead of the >> >> >> >> current ugly 'gen':'no'. >> >> >> >> >> >> >> >> In the long term, it will allow conversion from shorthand >> >> >> >> with defaults mentioned only in side-band documentation: >> >> >> >> 'data':{'*flag':'bool', '*string':'str'} >> >> >> >> into an explicit default value documentation, as in: >> >> >> >> 'data':{'flag':{'type':'bool', 'optional':true, 'default':true}, >> >> >> >> 'string':{'type':'str', 'optional':true, 'default':null}} >> >> >> > >> >> >> > FWIW, I don't think that's a very friendly syntax for >> >> >> > humans, it's a bit >> >> >> > verbose. But that's no reason not to allow true/false/null, of course. >> >> >> >> >> >> Here's my current thinking. >> >> >> >> >> >> 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. >> >> >> >> 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 :) >> > >> > What features does this Python mode provide that you use? >> >> Syntax highlighting, automatic indentation, possibly more I rely on >> without noticing. My fingers know, but they don't talk. >> >> > For the JSON schema, the only thing I really use from the editor is >> > syntax highlighting, and that shouldn't be bothered by an addition like >> > this (in vim it doesn't hurt anyway). I also don't use any other Python >> > tools, though I'm not sure that none exist that would make sense with >> > the schema. >> > >> > So if there are practically relevant advantages in being real Python >> > code, then we need to consider that, of course. That's why I was asking. >> > But if there aren't, it's just an arbitrary restriction that could be >> > removed. >> >> If we decide to revise the decision to borrow existing syntax and roll >> our own instead, let's 'make' 'our' 'own' 'syntax' 'not' 'suck'. >> >> Anyway, we got bigger fish to fry right now. > > Okay, I got it. Asking me to create a completely new syntax and the > generator for it is the longhand version for "no". It's advice, not a proactive NAK. Anyway, let's get Eric's series in, and crack the introspection problem before we start even more QAPI generator projects.