From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44517) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cpwqt-00007a-VC for qemu-devel@nongnu.org; Mon, 20 Mar 2017 08:56:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cpwqt-0005O4-4b for qemu-devel@nongnu.org; Mon, 20 Mar 2017 08:55:59 -0400 From: Markus Armbruster Date: Mon, 20 Mar 2017 13:55:47 +0100 Message-Id: <1490014548-15083-5-git-send-email-armbru@redhat.com> In-Reply-To: <1490014548-15083-1-git-send-email-armbru@redhat.com> References: <1490014548-15083-1-git-send-email-armbru@redhat.com> Subject: [Qemu-devel] [PATCH for-2.9 4/5] keyval: Document issues with 'any' and alternate types List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, kwolf@redhat.com, eblake@redhat.com Signed-off-by: Markus Armbruster --- util/keyval.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/util/keyval.c b/util/keyval.c index 46cd540..93d5db6 100644 --- a/util/keyval.c +++ b/util/keyval.c @@ -61,6 +61,16 @@ * "key absent" already means "optional object/array absent", which * isn't the same as "empty object/array present". * + * Design flaw: scalar values can only be strings; there is no way to + * denote numbers, true, false or null. The special QObject input + * visitor returned by qobject_input_visitor_new_keyval() mostly hides + * this by automatically converting strings to the type the visitor + * expects. Breaks down for alternate types and type 'any', where the + * visitor's expectation isn't clear. Code visiting such types needs + * to do the conversion itself, but only when using this keyval + * visitor. Awkward. Alternate types without a string member don't + * work at all. + * * Additional syntax for use with an implied key: * * key-vals-ik = val-no-key [ ',' key-vals ] -- 2.7.4