diff options
Diffstat (limited to 'include/qom/object.h')
| -rw-r--r-- | include/qom/object.h | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/include/qom/object.h b/include/qom/object.h index f9ad692f21..bd68d1938c 100644 --- a/include/qom/object.h +++ b/include/qom/object.h @@ -200,8 +200,14 @@ typedef struct InterfaceInfo InterfaceInfo; * * Interfaces allow a limited form of multiple inheritance. Instances are * similar to normal types except for the fact that are only defined by - * their classes and never carry any state. You can dynamically cast an object - * to one of its #Interface types and vice versa. + * their classes and never carry any state. As a consequence, a pointer to + * an interface instance should always be of incomplete type in order to be + * sure it cannot be dereferenced. That is, you should define the + * 'typedef struct SomethingIf SomethingIf' so that you can pass around + * 'SomethingIf *si' arguments, but not define a 'struct SomethingIf { ... }'. + * The only things you can validly do with a 'SomethingIf *' are to pass it as + * an argument to a method on its corresponding SomethingIfClass, or to + * dynamically cast it to an object that implements the interface. * * # Methods # * |