Message ID | 1328342577-25732-3-git-send-email-pbonzini@redhat.com |
---|---|
State | New |
Headers | show |
On 02/04/2012 02:02 AM, Paolo Bonzini wrote: > Signed-off-by: Paolo Bonzini<pbonzini@redhat.com> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com> And thank you very much for adding to the docs! Regards, Anthony Liguori > --- > include/qemu/object.h | 76 +++++++++++++++++++++++++++++++++++++++++++++++-- > 1 files changed, 73 insertions(+), 3 deletions(-) > > diff --git a/include/qemu/object.h b/include/qemu/object.h > index ab1c48c..ad7d32d 100644 > --- a/include/qemu/object.h > +++ b/include/qemu/object.h > @@ -55,6 +55,9 @@ typedef struct InterfaceInfo InterfaceInfo; > * > * #define TYPE_MY_DEVICE "my-device" > * > + * // No new virtual functions: we can reuse the typedef for the > + * // superclass. > + * typedef DeviceClass MyDeviceClass; > * typedef struct MyDevice > * { > * DeviceState parent; > @@ -88,8 +91,21 @@ typedef struct InterfaceInfo InterfaceInfo; > * > * Using object_new(), a new #Object derivative will be instantiated. You can > * cast an #Object to a subclass (or base-class) type using > - * object_dynamic_cast(). You typically want to define a macro wrapper around > - * object_dynamic_cast_assert() to make it easier to convert to a specific type. > + * object_dynamic_cast(). You typically want to define macro wrappers around > + * OBJECT_CHECK() and OBJECT_CLASS_CHECK() to make it easier to convert to a > + * specific type: > + * > + *<example> > + *<title>Typecasting macros</title> > + *<programlisting> > + * #define MY_DEVICE_GET_CLASS(obj) \ > + * OBJECT_GET_CLASS(MyDeviceClass, obj, TYPE_MY_DEVICE) > + * #define MY_DEVICE_CLASS(klass) \ > + * OBJECT_CLASS_CHECK(MyDeviceClass, klass, TYPE_MY_DEVICE) > + * #define MY_DEVICE(obj) \ > + * OBJECT_CHECK(MyDevice, obj, TYPE_MY_DEVICE) > + *</programlisting> > + *</example> > * > * # Class Initialization # > * > @@ -108,7 +124,61 @@ typedef struct InterfaceInfo InterfaceInfo; > * > * Once all of the parent classes have been initialized, #TypeInfo::class_init > * is called to let the class being instantiated provide default initialize for > - * it's virtual functions. > + * it's virtual functions. Here is how the above example might be modified > + * to introduce an overridden virtual function: > + * > + *<example> > + *<title>Overriding a virtual function</title> > + *<programlisting> > + * #include "qdev.h" > + * > + * void my_device_class_init(ObjectClass *klass, void *class_data) > + * { > + * DeviceClass *dc = DEVICE_CLASS(klass); > + * dc->reset = my_device_reset; > + * } > + * > + * static TypeInfo my_device_info = { > + * .name = TYPE_MY_DEVICE, > + * .parent = TYPE_DEVICE, > + * .instance_size = sizeof(MyDevice), > + * .class_init = my_device_class_init, > + * }; > + *</programlisting> > + *</example> > + * > + * Introducing new virtual functions requires a class to define its own > + * struct and to add a .class_size member to the TypeInfo. Each function > + * will also have a wrapper to call it easily: > + * > + *<example> > + *<title>Defining an abstract class</title> > + *<programlisting> > + * #include "qdev.h" > + * > + * typedef struct MyDeviceClass > + * { > + * DeviceClass parent; > + * > + * void (*frobnicate) (MyDevice *obj); > + * } MyDeviceClass; > + * > + * static TypeInfo my_device_info = { > + * .name = TYPE_MY_DEVICE, > + * .parent = TYPE_DEVICE, > + * .instance_size = sizeof(MyDevice), > + * .abstract = true, // or set a default in my_device_class_init > + * .class_size = sizeof(MyDeviceClass), > + * }; > + * > + * void my_device_frobnicate(MyDevice *obj) > + * { > + * MyDeviceClass *klass = MY_DEVICE_GET_CLASS(obj); > + * > + * klass->frobnicate(obj); > + * } > + *</programlisting> > + *</example> > * > * # Interfaces # > *
diff --git a/include/qemu/object.h b/include/qemu/object.h index ab1c48c..ad7d32d 100644 --- a/include/qemu/object.h +++ b/include/qemu/object.h @@ -55,6 +55,9 @@ typedef struct InterfaceInfo InterfaceInfo; * * #define TYPE_MY_DEVICE "my-device" * + * // No new virtual functions: we can reuse the typedef for the + * // superclass. + * typedef DeviceClass MyDeviceClass; * typedef struct MyDevice * { * DeviceState parent; @@ -88,8 +91,21 @@ typedef struct InterfaceInfo InterfaceInfo; * * Using object_new(), a new #Object derivative will be instantiated. You can * cast an #Object to a subclass (or base-class) type using - * object_dynamic_cast(). You typically want to define a macro wrapper around - * object_dynamic_cast_assert() to make it easier to convert to a specific type. + * object_dynamic_cast(). You typically want to define macro wrappers around + * OBJECT_CHECK() and OBJECT_CLASS_CHECK() to make it easier to convert to a + * specific type: + * + * <example> + * <title>Typecasting macros</title> + * <programlisting> + * #define MY_DEVICE_GET_CLASS(obj) \ + * OBJECT_GET_CLASS(MyDeviceClass, obj, TYPE_MY_DEVICE) + * #define MY_DEVICE_CLASS(klass) \ + * OBJECT_CLASS_CHECK(MyDeviceClass, klass, TYPE_MY_DEVICE) + * #define MY_DEVICE(obj) \ + * OBJECT_CHECK(MyDevice, obj, TYPE_MY_DEVICE) + * </programlisting> + * </example> * * # Class Initialization # * @@ -108,7 +124,61 @@ typedef struct InterfaceInfo InterfaceInfo; * * Once all of the parent classes have been initialized, #TypeInfo::class_init * is called to let the class being instantiated provide default initialize for - * it's virtual functions. + * it's virtual functions. Here is how the above example might be modified + * to introduce an overridden virtual function: + * + * <example> + * <title>Overriding a virtual function</title> + * <programlisting> + * #include "qdev.h" + * + * void my_device_class_init(ObjectClass *klass, void *class_data) + * { + * DeviceClass *dc = DEVICE_CLASS(klass); + * dc->reset = my_device_reset; + * } + * + * static TypeInfo my_device_info = { + * .name = TYPE_MY_DEVICE, + * .parent = TYPE_DEVICE, + * .instance_size = sizeof(MyDevice), + * .class_init = my_device_class_init, + * }; + * </programlisting> + * </example> + * + * Introducing new virtual functions requires a class to define its own + * struct and to add a .class_size member to the TypeInfo. Each function + * will also have a wrapper to call it easily: + * + * <example> + * <title>Defining an abstract class</title> + * <programlisting> + * #include "qdev.h" + * + * typedef struct MyDeviceClass + * { + * DeviceClass parent; + * + * void (*frobnicate) (MyDevice *obj); + * } MyDeviceClass; + * + * static TypeInfo my_device_info = { + * .name = TYPE_MY_DEVICE, + * .parent = TYPE_DEVICE, + * .instance_size = sizeof(MyDevice), + * .abstract = true, // or set a default in my_device_class_init + * .class_size = sizeof(MyDeviceClass), + * }; + * + * void my_device_frobnicate(MyDevice *obj) + * { + * MyDeviceClass *klass = MY_DEVICE_GET_CLASS(obj); + * + * klass->frobnicate(obj); + * } + * </programlisting> + * </example> * * # Interfaces # *
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- include/qemu/object.h | 76 +++++++++++++++++++++++++++++++++++++++++++++++-- 1 files changed, 73 insertions(+), 3 deletions(-)