From: Markus Armbruster Date: Mon, 20 Mar 2017 12:55:47 +0000 (+0100) Subject: keyval: Document issues with 'any' and alternate types X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0ee9ae7c8cda8b371b6b414c0d895feaec04f79e;p=qemu.git keyval: Document issues with 'any' and alternate types Signed-off-by: Markus Armbruster Message-Id: <1490014548-15083-5-git-send-email-armbru@redhat.com> Reviewed-by: Eric Blake --- diff --git a/util/keyval.c b/util/keyval.c index 46cd540c5a..93d5db6b59 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 ]