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Allow registering instance private data during get_type()

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For static types, it should be possible to register a private data
structure right when we are registering the type, i.e. from the
get_type() implementation. By allowing this, we can take advantage of
the existing type definition macros to cut down the amount of code
necessary (as well as the knowledge baggage) when creating a new type.

The main issue with this new feature is that it cannot be mixed with the
old idiomatic way of adding private instance data by calling a function
in the middle of the class_init() implementation, as that imposes the
additional constraint of initializing the whole type hierarchy in order
to retrieve the offset of the private data in the GTypeInstance
allocation.

For this reason we are going to follow a two-step process; in the first
step, we are going to introduce the new (semi-private) API to register
the intent to add private instance data from within the get_type()
implementation, and hide it behind a macro; at the same time, the
G_DEFINE_TYPE_EXTENDED macro is going to be modified so that it will
register the private instance data if the macro was used, using a new
(semi-private) function as well. Once we have migrated all our code, we
will make the first new function perform the actual private data
registration, and turn the second new function into a no-op. This should
guarantee a transparent migration of existing code to the new idiomatic
form.

https://bugzilla.gnome.org/show_bug.cgi?id=700035
This commit is contained in:
Emmanuele Bassi
2013-05-09 14:41:26 -07:00
parent 19e20084ab
commit bc3fcbf18d
5 changed files with 443 additions and 0 deletions
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104
gobject/gtype.h
View File

@@ -1284,9 +1284,15 @@ GType*g_type_interface_prerequisites (GType interface_t
GLIB_AVAILABLE_IN_ALL
void g_type_class_add_private (gpointer g_class,
gsize private_size);
GLIB_AVAILABLE_IN_2_38
gint g_type_add_instance_private (GType class_type,
gsize private_size);
GLIB_AVAILABLE_IN_ALL
gpointer g_type_instance_get_private (GTypeInstance *instance,
GType private_type);
GLIB_AVAILABLE_IN_2_38
void g_type_class_adjust_private_offset (gpointer g_class,
gint *private_size_or_offset);
GLIB_AVAILABLE_IN_ALL
void g_type_add_class_private (GType class_type,
@@ -1334,6 +1340,22 @@ guint g_type_get_type_registration_serial (void);
* Since: 2.4
*/
#define G_DEFINE_TYPE_WITH_CODE(TN, t_n, T_P, _C_) _G_DEFINE_TYPE_EXTENDED_BEGIN (TN, t_n, T_P, 0) {_C_;} _G_DEFINE_TYPE_EXTENDED_END()
/**
* G_DEFINE_TYPE_WITH_PRIVATE:
* @TN: The name of the new type, in Camel case.
* @t_n: The name of the new type, in lowercase, with words
* separated by '_'.
* @T_P: The #GType of the parent type.
*
* A convenience macro for type implementations, which declares a
* class initialization function, an instance initialization function (see #GTypeInfo for information about
* these), a static variable named @t_n<!-- -->_parent_class pointing to the parent class, and adds private
* instance data to the type. Furthermore, it defines a *_get_type() function. See G_DEFINE_TYPE_EXTENDED()
* for an example.
*
* Since: 2.38
*/
#define G_DEFINE_TYPE_WITH_PRIVATE(TN, t_n, T_P) G_DEFINE_TYPE_EXTENDED (TN, t_n, T_P, 0, G_ADD_PRIVATE (TN))
/**
* G_DEFINE_ABSTRACT_TYPE:
* @TN: The name of the new type, in Camel case.
@@ -1364,6 +1386,19 @@ guint g_type_get_type_registration_serial (void);
* Since: 2.4
*/
#define G_DEFINE_ABSTRACT_TYPE_WITH_CODE(TN, t_n, T_P, _C_) _G_DEFINE_TYPE_EXTENDED_BEGIN (TN, t_n, T_P, G_TYPE_FLAG_ABSTRACT) {_C_;} _G_DEFINE_TYPE_EXTENDED_END()
/**
* G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE:
* @TN: The name of the new type, in Camel case.
* @t_n: The name of the new type, in lowercase, with words
* separated by '_'.
*
* @T_P: The #GType of the parent type.
* Similar to G_DEFINE_TYPE_WITH_PRIVATE(), but defines an abstract type.
* See G_DEFINE_TYPE_EXTENDED() for an example.
*
* Since: 2.4
*/
#define G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE(TN, t_n, T_P) G_DEFINE_TYPE_EXTENDED (TN, t_n, T_P, G_TYPE_FLAG_ABSTRACT, G_ADD_PRIVATE (TN))
/**
* G_DEFINE_TYPE_EXTENDED:
* @TN: The name of the new type, in Camel case.
@@ -1487,17 +1522,86 @@ guint g_type_get_type_registration_serial (void);
g_type_add_interface_static (g_define_type_id, TYPE_IFACE, &g_implement_interface_info); \
}
/**
* G_ADD_PRIVATE:
* @TypeName: the name of the type in CamelCase
*
* A convenience macro to ease adding private data to instances of a new type
* in the @_C_ section of G_DEFINE_TYPE_WITH_CODE() or
* G_DEFINE_ABSTRACT_TYPE_WITH_CODE().
*
* For instance:
*
* |[
* typedef struct _MyObject MyObject;
* typedef struct _MyObjectClass MyObjectClass;
*
* typedef struct {
* gint foo;
* gint bar;
* } MyObjectPrivate;
*
* G_DEFINE_TYPE_WITH_CODE (MyObject, my_object, G_TYPE_OBJECT,
* G_ADD_PRIVATE (MyObject))
* ]|
*
* Will add MyObjectPrivate as the private data to any instance of the MyObject
* type.
*
* G_DEFINE_TYPE_* macros will automatically create a private function
* based on the arguments to this macro, which can be used to safely
* retrieve the private data from an instance of the type; for instance:
*
* |[
* gint
* my_object_get_foo (MyObject *obj)
* {
* MyObjectPrivate *priv = my_object_get_private (obj);
*
* return priv->foo;
* }
*
* void
* my_object_set_bar (MyObject *obj,
* gint bar)
* {
* MyObjectPrivate *priv = my_object_get_private (obj);
*
* if (priv->bar != bar)
* priv->bar = bar;
* }
* ]|
*
* Note that this macro can only be used together with the G_DEFINE_TYPE_*
* macros, since it depends on variable names from those macros.
*
* Since: 2.38
*/
#define G_ADD_PRIVATE(TypeName) { \
TypeName##_private_offset = \
g_type_add_instance_private (g_define_type_id, sizeof (TypeName##Private)); \
}
#define _G_DEFINE_TYPE_EXTENDED_BEGIN(TypeName, type_name, TYPE_PARENT, flags) \
\
static void type_name##_init (TypeName *self); \
static void type_name##_class_init (TypeName##Class *klass); \
static gpointer type_name##_parent_class = NULL; \
static gint TypeName##_private_offset; \
static void type_name##_class_intern_init (gpointer klass) \
{ \
type_name##_parent_class = g_type_class_peek_parent (klass); \
if (TypeName##_private_offset != 0) \
g_type_class_adjust_private_offset (klass, &TypeName##_private_offset); \
type_name##_class_init ((TypeName##Class*) klass); \
} \
\
static inline gpointer \
type_name##_get_private (TypeName *self) \
{ \
return (G_STRUCT_MEMBER_P (self, TypeName##_private_offset)); \
} \
\
GType \
type_name##_get_type (void) \
{ \