commit 3d3eacaeccaab718ea0e2ddaa578bfae9e311c59
author Marc-André Lureau <marcandre.lureau@redhat.com> Thu Apr 19 17:01:42 2018 +0200
committer Markus Armbruster <armbru@redhat.com> Fri May 04 08:27:53 2018 +0200
tree e0f8f345f94f9de6b203da0e4a8ff06b23e4c5ae
parent 7ee9edfdb117da47c86c9764d90f0be11a648666

qobject: use a QObjectBase_ struct

By moving the base fields to a QObjectBase_, QObject can be a type
which also has a 'base' field. This allows writing a generic QOBJECT()
macro that will work with any QObject type, including QObject
itself. The container_of() macro ensures that the object to cast has a
QObjectBase_ base field, giving some type safety guarantees. QObject
must have no members but QObjectBase_ base, or else QOBJECT() breaks.

QObjectBase_ is not a typedef and uses a trailing underscore to make
it obvious it is not for normal use and to avoid potential abuse.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180419150145.24795-3-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

qobject/qobject.c

diff --git a/qobject/qobject.c b/qobject/qobject.c
index 87649c5..cf4b7e2 100644
--- a/qobject/qobject.c
+++ b/qobject/qobject.c
@@ -37,9 +37,9 @@
 
 void qobject_destroy(QObject *obj)
 {
-    assert(!obj->refcnt);
-    assert(QTYPE_QNULL < obj->type && obj->type < QTYPE__MAX);
-    qdestroy[obj->type](obj);
+    assert(!obj->base.refcnt);
+    assert(QTYPE_QNULL < obj->base.type && obj->base.type < QTYPE__MAX);
+    qdestroy[obj->base.type](obj);
 }
 
 
@@ -62,11 +62,11 @@
         return true;
     }
 
-    if (!x || !y || x->type != y->type) {
+    if (!x || !y || x->base.type != y->base.type) {
         return false;
     }
 
-    assert(QTYPE_NONE < x->type && x->type < QTYPE__MAX);
+    assert(QTYPE_NONE < x->base.type && x->base.type < QTYPE__MAX);
 
-    return qis_equal[x->type](x, y);
+    return qis_equal[x->base.type](x, y);
 }